. Monographs of North American rodentia [microform]. Rodentia; Paleontology; Rongeurs; Paléontologie. il£u'.. ill'â â :::. t :U , 38G MOXOGKAPUS OF NORTH AMERICAN UODENTIA. hiiul feet, and in liaving a short, spiny, non-prehensile tail. The South Ameri- can genus ClicEtoinijs dillers from all of the others in the conformation of the skull; the malar hone is developed to a remarkable degree, more than in any other Rodent, excepting Calogenyn, the postorbital process of which nearly joins that of tlie frontal, so as to almost wholly separate the orbital and temporal fossae. The portion of t
. Monographs of North American rodentia [microform]. Rodentia; Paleontology; Rongeurs; Paléontologie. il£u'.. ill'â â :::. t :U , 38G MOXOGKAPUS OF NORTH AMERICAN UODENTIA. hiiul feet, and in liaving a short, spiny, non-prehensile tail. The South Ameri- can genus ClicEtoinijs dillers from all of the others in the conformation of the skull; the malar hone is developed to a remarkable degree, more than in any other Rodent, excepting Calogenyn, the postorbital process of which nearly joins that of tlie frontal, so as to almost wholly separate the orbital and temporal fossae. The portion of the palate between the molar teeth is also longer and narrower, and the temporal ridges arc more highly developed, wiiilc the molars themselves present important difiercnccs. The tail is lengthened and rat-like, scantily clothed with hair, and scaly, though to some degree prehensile. The genera Synethercs and Spkiiigurus differ somewhat from Erethizon in their cranial and dental characters, and have the tail strongly prehensile, while the feet (as also iti C/icctoiiii/.s) arc all four-toed. Syncthercs dilfers i'wm Sj>hingi/rus in the broad, highly arched form of the frontal region of the skull, and in the greater development of the spines. Chcetomys has l)ut a single species (f. subupinosus), which is confined to the nortliern and central portions of Brazil. Spliingurus and Syiwtheres have each several com- monly recognized species, which are distributed throughout the greater part of South and Central America, from Paraguay to Southeastern Mexico and the West Indies; none, however, occur west of the Andes. All the species arc of rather small size in comparison with tho representatives of Erethizon; the body rarely exceeding eighteen inches in length. Considerable variation in the form of the frontal region of the skull occurs among both the Hystricin(S and the Synethcrince. In this respect, Synetheres approaches Hystrix, while the Old AVorld genus Atherura, with its tl
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Keywords: ., bookcentury1800, bookdecade1870, bookpub, booksubjectpaleontology
