146 DB. c. I. roESYTH MAJOR oif THE [Feb. 19, 



a naso-]acrymal suture occurs, M'liich, however, is due to a 

 backward extension of the nasals. In four skulls the lateral 

 region of the fossa — the hamulus-region of the human lacrymal — 

 formed by the lacrymal is considerably enlarged. 



GhrysotTirix. 



Ch. sciureus (PI. XI. %. 7) and Ch. entomophagus ; 9 skulls.— 

 The lacrymal fossa and the whole of the lacrymal bone are 

 completely within the orbit. The maxilla, besides forming the 

 lower orbital margin, protrudes far below into the fossa, throwing 

 back the lacrymal. The frontal also generally advances into the 

 fossa, from above. It is a characteristic feature of GhrysotTirix 

 that the frontal descends unusually far below on the dorsum nasale 

 and inside the orbit, so that the fronto-niaxillary suture becomes 

 very large and often extends backwards into the upper part of the 

 fossa lacrymalis. 



Cebus. 



Forty-one skulls. — The lacrymal region is eminently "anthropo- 

 morphous " in all the species. The ansta posterior is situated at a 

 lower level than the crista anterior, which is convex forwards and 

 exclusively formed by the maxilla ; the latter not only delimits the 

 vi^hole anterior margin of the fossa, but descends into it and 

 occupies besides the whole of the antero-superior region, so that 

 there is generally a very broad fronto-maxillary suture. (An 

 exception is presented by one skull, C. capucinus, Br. M. No. 1049, 

 in which the nasal extends from its root backwards along the 

 upper margin of the maxillary, so that we have a lacrymo-nasal 

 suture within the fossa.) The upper part of the fossa appears 

 continued on the frontal, the crista posterior, and sometimes 

 {G. xanthocephalus) both the c. ant. and c. post., being continued 

 on that bone. 



Hapalib^. 



The fossa lacrymalis is decidedly orbital. As a rule, the whole 

 of the crista anterior is formed by the maxillary, which descends 

 into the fossa. 



Hapale. 



Nineteen skulls examined. — A. lacrymo-nasal suture occurs in 6 

 out of the 19 specimens. The os planum encroaches upon the 

 lacrymal from behind ; the crista posterior is formed solely by the 

 lacrymal as a rule, but sometimes the os planum partakes in its 

 formation. In H. jacchus the upper part of the crista anterior is 

 rather flattened, so that the lacrymal encroaches upon the face, and 

 the fronto-maxillary suture either becomes very shortened or is 

 replaced by a lacryroo-nasal suture (in three specimens of this 

 species). The os planum helps to join the crista posterior in one 

 specimen of this species (Br. M. No. 1216 b) . In two out of four 

 specimens of II. aurita we have a lacrymo-nasal suture ; besides 



