384 Zoological Society : — 



highly desirable when we bear in mind the small size of the objects, 

 and the consequent difficulty of rendering apparent their differences 

 without the aid of figures. They will be described in the following 

 order, the crania of the two species most removed from each other 

 being found to be most dissimilar. 



N. Ti7noriensis. — General form of the skull rather broad and flat, 

 and rather thick in substance ; sagittal and occipital crests mode- 

 rately developed ; depression of the nasal bones of nearly equal 

 depth from side to side, broad, with the sides parallel for three- 

 fourths of its length in a backward direction, and then narrowing 

 rapidly to a point at the commencement of the sagittal ridge. Fa- 

 cial portion short ; zygomatic arches considerably expanded. Palate 

 nearly as wide anteriorl}'^ as posteriorly. Lower jaw strong, its lower 

 margin considerably curved. All the teeth of moderate size and 

 proportions. 



N. Gouhli. — General form of the skull much less broad than in 

 the last species, more elevated in the crown, and narrower anteriorly; 

 sagittal crest considerably developed, the occipital one very small ; 

 facial depression almost obsolete, narrow, rounded-off on each side, 

 and only amounting to a concavity just at the posterior termination 

 of the nasal bones. Facial portion relatively more produced than in 

 the last species ; zygomatic arches but little expanded. Palate much 

 narrower in front than behind. Lower jaw as in the last species. 

 All the front teeth, especially the upper canines, vei-y short and 

 stout. 



N. unicolor. — General form of the skull very short, as broad re- 

 latively as in the first species, but not so flat, and much lighter and 

 thinner in substance than in either of the preceding ; sagittal ridge 

 merely rudimentary, occipital one considerably elevated, especially 

 its central portion ; facial depression broad, of medium depth, well- 

 defined, and narrower before and behind than in the middle, and 

 with the outline of the nasal bones rather distinctly marked. Facial 

 portion of medium length ; orbits much produced in a forward di- 

 rection, leaving but a small space between them and the roots of the 

 canines ; zygomatic arches a good deal expanded. Palate short, 

 nearly as broad in front as behind. Lower jaw short and light, with 

 a moderate degree of curvature. All the front teeth short and 

 small. 



N. Geoffroyi. — General form of the skull differing from that of 

 all the others. It is rather long, narrow, and depressed, with a total 

 absence of ridges or crests, and the occipital region rounds-oflF poste- 

 riorly without any angularity. It is thin and somewhat dia})hanous ; 

 facial depression narrow, deep in the centre, not clearly defined an- 

 teriorly, and passing further back than in the other species, its 

 posterior portion being indicated by two thread-like lines which con- 

 verge to an acute point on the fore part of the central region. Facial 

 portion of medium length, and narrowed anteriorly ; zygomatic 

 arches but very little expanded. Palate much narrower in front 

 than behind. Lower jaw slender, with the lower outline nearly 

 straight. Front teeth proportionally long and rather strong. 



