406 PROFESSOR PETERS ON THE GENUS PECTINATOR. 
Digestive Organs. 
The mucous membrane of the roof of the mouth forms a triangular pointed elevation 
in front, two transverse ridges before, and five irregular ridges between the molar 
teeth (Pl. L. fig. 15). 
The tongue (fig. 16) is elongate, with a rounded point. Its upper surface is covered 
with very minute homogeneous papille, and provided with only two papille vallate. 
The sublingual glands are lengthened and of moderate size, the submaxillary and 
parotid glands very large. 
The hyoid (fig. 17) forms a nearly straight transverse bone, compressed in the antero- 
posterior direction, with a nearly straight upper and a concave lower margin. ‘The 
anterior horns are articulated, the posterior immovably attached by an intermediate 
cartilage, and articulating with a process of the thyroid cartilage. It resembles, there- 
fore, much more that of Mus than that of Dipus, and is very different from the arched 
hyoid, with a spine-shaped anterior process, of Chinchilla, Echinomys, &c. 
The fauces are very straight; and the palate has no uvula. The pharynx and 
cesophagus are narrow, and have together a length of 60 millims. The cesophagus 
opens, as is usual in the Rodents, into the middle of the upper curvature of the simple 
stomach (fig. 18), which measures about 50 millims., and is at both ends nearly of the 
same volume. It contained only small pieces of triturated vegetables’. The small 
intestine begins with a dilated duodenum, and has a length of 145 milims. The large 
intestine is puckered, and is 550 millims. long, of which the lower part, with the 
rectum, for a length of 25 millims., is much narrower. ‘The cecum (fig. 19) is 45 
millims. long, and about 17 millims. in diameter. 
The liver (fig. 18) is, in different individuals, of very different size. ‘The pyriform gall- 
bladder is placed in the fissure of the middle lobe; the right lobe has a distinct lobulus 
caudatus and lobulus Spigelii; the left lobe is undivided and flattened, with a sharp 
margin. 
The spleen is lengthened, flattened, and nearly tongue-shaped. ‘The pancreas is, 
as usually in Rodents, flattened and branched, but less expanded than in Mus, and 
apparently more like that of Chinchilla, which latter, however, I have not been able to 
examine in a perfect state. Towards the duodenum it becomes larger, but at the same 
time less compact. 
Heart and Organs of Respiration. 
The heart (fig. 17) has an oval form, a length of 15 millims., and a width of 9 millims. ; 
the apex of the left ventricle is very prominent. ‘The aorta (a) gives off a truncus com- 
munis, which, after having emitted the right subclavian, divides into the two carotids, 
while the left subclavian originates as a separate stem. ‘Two upper vene cave, a right 
and a left one, enter into the right auricle. 
The epiglottis shows on the middle of its free margin a little rounded prominence. 
1 Heuglin says that Pectinator spekii feeds on buds, leaves, bark, and perhaps also on grain. 
