194 Fretp Museum or Naturat History — Zoétroey, Vor. X. 
ish at the base, the ears are thinly haired and dusky, and in the skull the 
jugal has a well-developed postorbital process. In all of these respects 
D. nigriclunis is markedly different, the sides of the rump being mixed 
tawny and black, the long rump hairs are dark drab at the base, the 
ears are hairy and light ferruginous in color, and in the skull the jugal 
shows scarcely an indication of a postorbital process. The type of 
D. nigriclunis is slightly immature, for although the last molar is up in 
place and somewhat worn, the milk tooth is still in the last stages of 
functional condition. It is possible that an older individual might show 
some development of a postorbital process of the jugal, but this is 
rendered improbable by the fact that in various of the yellow-rumped 
species it is well marked in specimens younger than the type of nigri- 
clunis. 
Caviella subg. nov. 
Type, Cavia australis Geoffroy & D’Orbigny. 
Characters:— Intermediate, in a broad sense, between Cavia and 
Galea, having certain general cranial characters of Cavia and dental 
characters of Galea; palatine foramina large and roughly triangular, 
their length at least half the diastema; orbital branch of maxillary con- 
tinuous as in Cavia, not broadly interrupted by lacrymal as in Galea; 
palate with a central ridge and deep lateral channels; rostral and inter- 
orbital region nearly flat, not laterally sloping; lateral boundary of 
rostrum formed almost entirely by the premaxillae, the shelflike develop- 
ment of the maxillaries found in Cavia and Galea being so reduced that 
the lower border of the infraorbital foramen is clearly visible when the 
skull is viewed from directly above; incisors projected well beyond the 
nasals, unpigmented as in Cavia; cheekteeth closely similar to those of 
Galea, the enamel loops of the middle teeth nearly equal in size and the 
posterior loop with no angle on its outer side. 
Remarks:— Examination of a considerable series of skins, skulls, 
and skeletons of various species usually referred to Cavia and Kerodon 
indicates that a natural arrangement of generic and subgeneric groups 
requires some changes in the application of names. The name Kerodon 
should be restricted to one species, Kerodon rupestris, which not only 
differs from the others in habits, in external characters, and in cranial 
characters, but in important skeletal characters. Chief of these are the 
narrow and rounded instead of flattened sternum, the thick, heavy, and 
depressed spinous processes of the lumbar vertebree, the large neural 
spine of the axis fully overlapping the first cervical, and the transverse 
processes of the atlas which are singly instead of doubly perforated on 
