Horatio C Wood, Jr.

“ The Diplopods depend upon the vegetable kingdom for their sustenance. The body is much more rigid than in the Chilopods, from the close conjunction, or often imbrication, of the segments, and the inflexibility of the segments themselves, caused by the density and thickness of the scuta aud sterna and the absence of lateral membranes. For this reason the Diplopoda possess but little or none of that power of raising and twisting the body, which is so annoying to the collector of tropical Scolopendra. ”

“ The body in the Chilopoda is composed of segments, whose number varies from sixteen to several hundred. Each segment is furnished with a single pair of legs. There might seem to be an exception to this in the Cermatiidæ, but close examination shows that in them the fact of there being but one scutum to two segments is the cause of the apparent anomaly. In all the other families there is a scutum and sternum to each segment. These external bones, so to speak, are connected by a tough membrane, which forms the only protection to the sides. ”

“ The posterior legs furnish the best criteria in the distinguishing of species. Most species have peculiarities either in the shape or relative size of the joints, or in the number or arrangement of spines on them. In order to show the amount of constancy that these characters possess, I have drawn up a series of tables, which may aid in establishing their value. The color, I think, is not to be depended upon, although Mr. Newport seems to attach much importance to it. In the preservation of specimens it is very liable to be altered or destroyed ”

“ It is noticeable that the terminal scutum has a single median, instead of two lateral sutures. The preanal scale is rather large, much narrowed, and very slightly emarginate posteriorly. Where the marginal spines of the lateral anal appendages exceed two in number, some of them are generally very small and situated at or near the base of the terminal process. I have named this species in honor of Prof. Edward D. Cope, with whom it has been my good fortune to have been associated since the earliest dawn of our tastes for natural history. ”

“ As a general rule, the fewer the segments the higher the organization. Each perfected segment is formed from two subsegments, either by their coalescence and mutual growth, or by the atrophy of one and the hypertrophy of the other. The dorsal and ventral portions of the subsegments are each formed originally from four pieces. The two central unite very early in the embryo, and completely fusing form the primitive scuta and sterna, with which the outer pieces, the episcuta and episterna, unite sooner or later. ”

“ The under surface of the body is light-colored, and is often somewhat areolated. There are some specimens whose pattern of coloration is light brown or fawn colored, with two lateral and one median dark stripe. Are these individuals which have recently cast off their exuviæ? The eye-patches are somewhat parabolic. The joints of the antennæ are obconical, dark colored, and tipped with white. The lateral processes are small. The grooving of the scuta is in some specimens somewhat obsolete on the dorsum. The posterior scutum is light colored. I have never identified a male. ”

“ There can be no doubt but that they are provided with poison glands situated at the base of the mandibular teeth, and perhaps also at the bases of the terminal claws of the feet. I remember once to have been bitten by a female Scolopocryptops sexspinosa, who was trying to defend her young. Though of such insignificant size, when compared with the tropical Scolopendra, yet the pain produced lasted for several hours. It is therefore easily to be imagined that the huge species, a foot in length and inch in breadth, found in the tropics, have the power of doing considerable mischief. ”

“ The antennæ are formed according to the type of the Diplopoda, with seven joints. The body is composed of numerous segments. The scuta may be prolonged laterally into laminæ, but afford protection only to the back and flanks; the central part of the abdomen is not covered by a firm, resistant shell. The feet are hidden beneath the broad body. The male genitalia are placed in the seventh segment. In the classification of the families and genera I have followed Mr. Brandt, [26] his arrangement, as far as the two species I have seen enable me to judge, being founded on natural characters. ”

“ The head varies very much in size and the perfection of its organization, but is always separate and distinct. The organs of special sense are very well developed in all but the lowest orders. The eyes are in one family compound, in the others stemmatous and single or numerous, or else entirely wanting.
The body is composed of a varying number of segments, most of which are merely a repetition of the preceding. ”

“ On glancing over the Chilopoda it will be seen that, as we descend the scale, the number of segments in the body constantly increases—or, in other words, the distinctive character which separates the Myriapods from the Hexapods and Crustacea, and allies them to the Annelids,—the multiplicity of segments, the absence of cephalization—is exaggerated. On applying this principle, it will be at once perceived that the Polydesmidæ must be placed above the Iulidæ, and the Glomeridæ, Leach (of Newport) , be still higher, and thus be thrown next to the first order. ”

“ Although this monograph of a single faunic group is not the place for a discussion of the history of the classification of the Myriapoda, yet it has seemed necessary to make this brief notice of and comparison between the works of the more recent authorities, before introducing what appears to the author to be the natural arrangement, which has been gradually developed by the various efforts; each adding something, each pushing forward a little towards the truth. ”

“ The basal portion of the mandibles on each side project, so that if a vertical section of the head through the middle were taken it would be an oval with its greater diameter transverse. The eyes are in strictly triangular patches, with remarkably straight sides. The scuta are so deeply canaliculate along their dorsal centre as to be almost divided into two parts. The dorsum is not perfectly rounded, but there is somewhat of a ridge or angle in the centre. Each scutum is furnished with a regular series of distant large puncta, or perhaps more properly, pores. ”

“ I have therefore divided the Diplopoda into two suborders, the Chilognatha and Sugentia, retaining old names, but giving new significance to them. The minor characters have seemed to me to confirm this, and to indicate that it is coincident with the plan on which the Myriapoda have been created. M. Brandt (Recueil, p. 26) divides the Chilopoda into the Schizotarsia and Holotarsia. ”

“ Surface markings more generally characterize small groups than individual species, yet are sometimes available even in closely allied forms. The possession of a mucro characterizes groups; whilst its size and its shape are often specific. As in all the other Diplopoda each species has a peculiar and persistent form of the Genitalia, more marked in the male than in the female. Indeed a certain type of arrangement seems in this group to characterize a genus.
Genus IULUS.
Scutum primum magnum, lateribus in femina nonnihil productis. ”

“ In like manner, in the Lithobiidæ, the second cephalic scutum is very small, agreeing with the smaller scuta of the body.
The arrangement of the Chilopoda adopted in this memoir is very nearly that of Mr. Newport, which appears to be the true exposition of the plan of their creation. His families are natural, and are grouped according to their affinities. The Cermatiidæ deservedly stand at the top, on account of their more perfect organization and approach in some characters towards the Hexapoda. They have, as has been just stated, but a single scutum to two segments. ”

“ Newport and others have not allowed these characters the weight that they deserve. Mr. Gray does not even allow them generic force, if his classification (Cyclop. Anat. and Physiol., art. Myriap.) is to be trusted. Or was he entirely ignorant of their existence! Newport gives to them a family significance.
The different structure of the mouth, and the consequent different food and habits of living, although not sufficient to stand in competition with the characters separating the Chilopoda and Diplopoda, are still of higher import than any other differences in the latter order. ”

“ Conjoined and posterior to the coxa of the second cephalic subsegment we will find a large plate (a) articulating with the cephalic scutum by suture; this I take to be the primitive sternum and episternum of the third cephalic subsegment atrophied and fused together; to it the true maxilte are articulated. These consist each of, first an elongated crooked plate (the coxa) articulating with two plates, the exterior of which (the femur) is armed with a tubercle, as in the mandibles, posterior legs, &c.; the inner plate is the tibia ”

“ In some individuals there exists a well-pronounced black, median, dorsal line. In others the pattern of coloration approximates that of P. corrugatus; but I have never seen a well-pronounced margination of the scuta. There may be some doubt as to whether this is the species intended to be indicated in the original description of P. Virginiensis, which would apply probably equally well to several species. ”

“ The organization of this family is more fitted for activity and their habits less sluggish than in the Polydesmidæ, although less so than in the Spirostrephonidæ. The coloration varies, some species being ornamented with annuli, others with stripes. The only surface markings, in our American species at least, consist of longitudinal channels, or flutings and punctations.
The American species are comprised in two genera, lulus, Spirobolus. Some authors recognize a third genus, Uncigera, founded or the presence of a mucro or point on the posterior scutum. ”

“ It is possible that it may vary in certain species; but the differences generally consist in there being too few joints, which, as has been just stated, is to be looked for, and reproduced antennæ probably have occasionally an abnormally great number of very small articles. The number and arrangement of the labial teeth sometimes constitute a good character, but there is often an agreement between distinct forms, and on examining large suites of individuals, I have found more variance in the same species than reading would lead one to look for. ”

“ Light yellow; body very depressed, rather broad, anteriorly slightly narrowed; head large; cephalic segment subtriangular; antennæ short, moniliform, posteriorly slightly depressed, thick, anteriorly cylindrical, not acuminate, with a few soft, very short hairs; labium short, broad, anteriorly obsoletely bidentate, impressed with a slightly pronounced median sulcus; mandibles thick; scuta very short, without sutures, but with sometimes an obscure median line; sterna very short, each with a single submedian ovate depression, most conspicuous on the anterior portion of the body ”