Walter Woelber Dalquest

“ Comparison.—From Myotis albescens (E. Geffroy) known to us by specimens in the United States National Museum from Paraguay (Tacural) , Panama (Tabernilla) , and Nicaragua (Prinzapolca R. and Escondido R.) , argentatus differs in: Body and foot longer; tail relatively shorter (57 and 58% of length of head and body versus 76 (62-83) % in albescens) ; tibia shorter; pelage longer, and black instead of brown; silver tipping of fur on hinder back markedly more conspicuous; precranial part of skull, when viewed from above, larger in relation to brain case ”

“ At that instant two bats were detected in one of the many small holes in the trunk, which was eight to nine inches in diameter. It was a simple matter to enlarge the hole and extract the animals. Superficially they resembled silvery-haired bats (Lasionycteris) but their naked interfemoral membranes and other features suggested that they belonged to the genus Myotis. Subsequently, study in the laboratory showed this to be the fact and revealed also that they are of an heretofore unnamed species which may be known as:
Myotis argentatus, new species
Type.—Male, adult, skin with skull, No. ”

“ Head and body, 55, 51 mm.; tail, 32, 29; tibia, 13.7, 13.2; foot, 8, 9; forearm, 33.0, 34.5; thumb, 5.8, 5.7; third metacarpal, 32.2, 30.5; fifth metacarpal, 31.5, 30.3; greatest length of skull, 14.5, 14.0; condylobasal length, 13.8, 13.0; zygomatic breadth, 9.1, 9.0; interorbital constriction, 4.3, 4.0; breadth of brain case, 7.5, 7.4; occipital depth, 5.7, 5.7; mandible, 10.5, 10.0; maxillary tooth row, 5.3, 5.0; maxillary breadth at M3, 5.5, 5.7; mandibular tooth row, 5.6, 5.3.
Specimens examined.—Two, from the type locality. ”