Ischium

“ The determination of the structure of the shoulder-girdle threw open the homology of this bone, which clearly could not be a clavicle, whatever else it might be. The alternative position once more lay in the pelvis, and this time between the ischium and the pubis; and as the ilium was bird-like, might not the ischium, or pubis, be also expected to be ornithic in form? At any rate the bone answered remarkably well to the ischium of one of the Ratitæ.
Resemblances to the structures found in some birds had already been noted by Prof. Owen [1] in the sacrum of the Dinosauria ”

“ The most characteristic features of the group are found in the pelvis which, except in the Ceratopsia, bears a striking resemblance to that of birds. The ischium and post-pubis are long slender bones directed backwards parallel to one another, and the pre-pubis is also well developed. The ischium has an obturator process. The limb bones are sometimes hollow, sometimes solid. The anterior limbs are much shorter than the posterior, pointing to a bipedal method of progression. The pes is digitigrade or plantigrade, and has three, rarely four, digits. ”

“ The os innominatum has three primary centres for the ilium, ischium and pubis.
The special centres for the crest of the ilium are probably a serial repetition of those for the vertebral border of the scapula (see fig. 19) ; that for the anterior inferior spine is a purely human traction epiphysis connected with the use of the straight head of the rectus femoris in the upright position. The centre for the pubic symphysis probably represents the epipubis of amphibians, while that for the tuberosity of the ischium is the hypoischium of reptiles (see sub- section on comparative anatomy) . ”

“ A left ischium is preserved only missing the articular surface of the iliac peduncle and pieces from the distal margin. The ischium is large and expanded ventrally into a broad relatively thin blade. The iliac peduncle is distinct from the neck leading to a large open acetabulum. In cross-section the iliac peduncle is ovoid with a constricted cranial margin, which extends into a sharp crest which borders the acetabular rim and joins the pubic peduncle. The pubic peduncle merges with the pubic articular surface and the distal articular surface into a single straight pubic articulation. ”

“ In the Marsupialia the ilia are generally very simple, straight, and narrow, while the pubes and ischia are well developed and meet in a long symphysis. Marsupial bones are nearly always prominent, but are not developed in Thylacinus or Notoryctes. The ischium often has a well-marked tuberosity and in Kangaroos the pubis bears a prominent pectineal process on its anterior border close to the acetabulum. The pelvis in Notoryctes differs much from that in all other Marsupials, the ilium and ischium being ankylosed with six vertebrae in a manner comparable to that of many Edentates. ”

“ But to name this great pelvic bone was a difficulty with me. I was under the impression that its broad, smoothly expanded surface might be best compared with that of an ischium [3] or pubis, and that this would be more suited to the broad depressed body (as I supposed it to be) of such a huge creature, than, by accepting it as an ilium, to admit the beast to have been narrow in the rear, like a bird, with the plane of the bone not much inclined from the vertical. ”

“ Birds have a very large pelvis and its characters are constant throughout almost the whole group. The ilium is very large, and is united along its whole length with the sacral and pseudosacral vertebrae. The ischium is broad and extends back parallel to the ilium with which in most [340] birds it fuses posteriorly, further forward the ilio-sciatic foramen separates the two bones. In Tinamus, Hesperornis, Apteryx (fig. 65, B, 2) , and Struthio, the ischia are separate from the ilia along their whole length except at the acetabulum ”

“ The lateral ischiatic ridge is a relatively slight ridge continuous with the posterior end of the lateral iliac process and curves posteroventrally across the lateral surface of the posterior part of the ischium; the ridge extends to the ventral edge of the ischium in some individuals and not in others. The dorsolateral iliac ridge begins at the lateral edge of the ilium near the posterior end of the lateral iliac process and curves posteromedially and somewhat dorsally, extending to the posterior edge of the ilium. ”

“ The pubes and ischia are fused along the mid-ventral line. Many morphologists regard, the ilium as equivalent to, that is, strictly corresponding in its relation, to the scapula, the pubis to the cartilaginous substratum of the clavicle, and the ischium to the coracoid.
Section 85. These bones will be studied at the greatest advantage when dissected out from a boiled rabbit. Prepared and wired skeletons, disarticulated skeletons, plates of figures, and written descriptions are in succession more tedious and less satisfactory ways to a real comprehension, of this matter. ”

“ In many reptiles such as Chelonia, Ichthyosauria and Lacertilia the ilia are small, more or less cylindrical bones either directed backwards, or vertically placed as in the Chamaeleons. In the Crocodilia they are larger and more expanded, while in Dinosauria and Pterosauria they are greatly elongated both in front of, and behind, the acetabulum. The ischia are generally strongly developed somewhat square bones meeting in a ventral symphysis. In Dinosauria the ischium (fig. 35, 9) is a much elongated and backwardly-directed bone, [292] bearing a forwardly projecting obturator process. ”

“ In some Labyrinthodonts the pubes as well as the ischia meet in a ventral symphysis, and in many there are no obturator foramina. In Siren, Gymnophiona and some Labyrinthodontia the pelvic girdle and limbs are absent.
In Urodela the ventral element of the pelvis on each side forms a flat plate which meets its fellow of the opposite side. The anterior part of the plate, representing the pubis, generally remains cartilaginous throughout life; the posterior part representing the ischium is in almost every case well ossified. ”

“ Il, ilium ; a, b, its anterior and posterior extremities; Is, ischium, Pb, pubis; Tr, trochanter of the femur of the Dinosaur; T, tibia; F, fibula; As, astragalus; Ca, calcaneum; 1, the distal division of the tarsus; I, II, III, IV, V, the digits. Thus the ischia of a Dinosaurian are more bird-like than those of any existing reptile, but retain the reptilian union in a symphysis. 3. In all reptiles the pubis is inclined forwards as well as downwards towards the ventral median line. In all except the Crocodile it takes a considerable share in the formation of the acetabulum ”

“ Ischia stronger than the pubic bones, which are distally much broadened. The femur is nearly three feet long, and possesses a fourth trochanter. The astragalus has an ascending process, and is fused with the tibia. The toes are short, strong, and clawed. The shoulder-girdle and fore-limb are strong, the latter well adapted to grasping. The teeth are much compressed laterally, with sharp, finely serrated edges. Several allied genera have been described from the Upper Trias of France and England: others from corresponding strata of India and South Africa. ”

“ The ischia, on the other hand, are always connected with each other, not so much by fusion as by syndesmosis.
The hind-limbs exhibit all stages from a simple, plantigrade and five-toed state to a decidedly digitigrade, four, and even three-toed arrangement. Many genera exhibit the tendency to form an intertarsal joint, a feature elsewhere known in birds only, where it is typical and universal. The astragalus sends up an ascending process which tends to fuse with the anterior aspect of the distal end of the tibia, and the calcaneum is sometimes more or less firmly attached to the fibula. ”

“ He stands on the bank of a beautiful stream clear as crystal, or in the midst of the water, but when he attempts to quench his raging thirst it is impossible even to wet his lips. Sisyphus, once king of Corinth, and a great sinner, was condemned to roll a block of stone up a high mountain, but, soon as the top was reached, the huge stone, by some sudden impulse, rolled back to the plain, and with weary limbs he must continue the fruitless struggle. Ixion, also an insolent offender, is chained, hands and feet, to an ever revolving wheel and tortured without respite or hope of release. ”

“ The pelvis is very strong; the broad pubes and ischia meet in the middle line, and they either enclose one wide undivided foramen, or the two symphysial portions meet, and there are then two obturator-foramina. The pubes are generally much larger, especially broader, than the ischia; and although partaking in the formation of the acetabulum, they do not articulate with the ilia, at least not in Plesiosauri. The ilia are always small; in Plesiosauri attached to only one or two sacral ribs; to three or four in the Triassic genera. ”

“ But the glory of Italy is in her sunsets, and toward evening sea and mountain, tufa rock and yellow sand, put on a marvellous robe, a veritable "coat of divers colors," and life seems to breathe and sigh in things that before seemed lifeless.
Ischia, like all Italian localities, has its patron saint; they call her Santa Restituta.
When persecution was raging in Egypt, in the third century, says the simple legend, the body of a young [277] maiden, with a millstone tied round her neck, floated across the sea and rested in a creek on the south side of the island. ”

“ Jupiter played piquette with Mercury.
‘Everything goes wrong to-day,’ said the King of Heaven; ‘cards wretched, and kept waiting for dinner, and by——-a mortal!’
‘Your Majesty must not be surprised,’ said the good-natured Mercury, with whom Ixion was no favourite. ‘Your Majesty must not be very much surprised at the conduct of this creature. Considering what he is, and where he is, I am only astonished that his head is not more turned than it appears to be. A man, a thing made of mud, and in Heaven! Only think, sire! Is it not enough to inflame the brain of any child of clay? ”

“ Amazed, I listened to this wonderful tale of toil and patience, extending over the greater part of half a century, and amazed, I looked down at the result of this labour of Sisyphus, the framents of brown dust—they could have been little else—which now, after thousands of years, had revealed secrets which Hugh said would set the world gaping. My knowledge of Egyptology and hieroglyphics had become somewhat rusty since the happy days when, sitting in the room in the fitful light of the fire, I used to hear from the dear old man's lips the wonders of Khefren and the mysteries of Queen Neit-akrit ”

“ Good-bye!’ And so saying, the God pulled a couple of arrows from his quiver, and with the rapidity of lightning shot one in the respective breasts of the Queen of Heaven and the King of Thessaly.
The amethystine twilight of Olympus died away. The stars blazed with tints of every hue. Ixion and Juno returned to the palace. She leant upon his arm; her eyes were fixed upon the ground; they were in sight of the gorgeous pile, and yet she had not spoken. Ixion, too, was silent, and gazed with abstraction upon the glowing sky. ”

“ The name of Ixion has been identified with the Sanskrit word Akshanah, denoting one who is bound to a wheel, and has been proved akin “to the Greek axôn, the Latin axis, and the English axle.” This whirling wheel of fire is the bright orb of day, to which he was bound by order of Jupiter (the sky) because he dared insult Juno (the queen of the blue air) ; while Dia, his wife, is the dawn, the counterpart of Europa, Coronis, Daphne, Procris, Eurydice, and Venus, in the foregoing illustrations. ”

“ In some Lacertilia and Chelonia there is a cartilaginous bar dividing the foramen cordiforme into two obturator foramina; in many Chelonia this bar is ossified. Among Ophidia, Python, Tortrix, Typhlops and their allies have a structure representing a vestigial ischio-pubis: but in most Ophidia there is no trace of the pelvis. In some Theromorpha all the bones of the pelvis are completely fused, forming an os innominatum as in mammals; the pubes and ischia are so completely fused that sometimes as in Pariasaurus even the obturator foramina are closed. ”

“ They are a singular race, graceful in movement.
Evening is divine in Ischia. From the topmost garden terrace of the inn one looks across the sea towards Terracina, Gaeta, and those descending mountain buttresses, the Phlegræan plains, and the distant snows of the Abruzzi. Rain-washed and luminous, the sunset sky held Hesper trembling in a solid green of beryl. Fireflies flashed among the orange blossoms. Far away in the obscurity of eastern twilight glared the smouldering cone of Vesuvius—a crimson blot upon the darkness—a Cyclops' eye, bloodshot and menacing. ”

“ Ganymede ran forward, and dashed open the door. Ixion was alone.
‘Seize him!’ said Jove.
‘Juno is not here,’ said Mercury, with an air of blended congratulation and disappointment.
‘Never mind,’ said Jove; ‘seize him! He kept me waiting for dinner.’
‘Is this your hospitality, Ægiochus?’ exclaimed Ixion, in a tone of bullying innocence. ‘I shall defend myself.’
‘Seize him, seize him!’ exclaimed Jupiter. ‘What! do you all falter? Are you afraid of a mortal?’
‘And a Thessalian?’ added Ganymede. ”