144 DB. C. I. rOESYTH MAJOR ON THE [Feb. 19, 



Ateles, 



In 14 out of 25 specimens examined, the fossa laci^ymalis was 

 completely encircled by the lacrymal (PI. XII. figs. 4 & 6), in six 

 more cases the maxilla merely touched the fossa near_ its antero- 

 inferior border. Only in five specimens Avas found a slightly more 

 extended maxillary margin of the fossa, such as figured by Gegen- 

 baur\ The supero-anterior angle of the lacrymal also protrudes 

 more on the face than suggested by the mentioned figure. A 

 lacrymo-nasal suture vcas found in 12 cases (PL XII. figs. 4 & 6) ; 

 a mixed condition, viz. a lacrymo-nasal suture on one side pnly, 

 in three cases. Only in eight cases did I find a fronto-maxillary 

 suture, which is always very limited, as described by Gegenbaur.^ 



It cannot be said that in every case the fossa lacrymalis is 

 decidedly extra-orbital ; this condition is rather an exception in 

 Ateles, occurring when the crista posterior is more than usually 

 prominent. Where the orbit presents no marked limits in this 

 region, it is, as with Mycetes, a matter of mere individual appre- 

 ciation whether we have to regard the fossa as lying inside or 

 outside the orbit. That there are variations in this respect in 

 Ateles, was already known to Gr. Fischer, who says that in a skull of 

 A. paniscus the aperture of the lacrymal canal was situated " auf 

 der Grenze der Augenhohle, oder auf seinem (sic !) Eande, aber 

 doch immer mehr nacb innen," whilst other skulls of tbe same 

 species presented the same conformation as in the other species ^. 



BracJiyteJes. 



The skull of this rare monkey, of which I could examine only 

 seven specimens — one in Leyden, six in the Natural History 

 Museum — exhibits a very broad interorbital region, due in a great 

 measure to the large development of the lacrymal. In spite of 

 this, the anterior boundary of the fossa is for the greater part — in 

 one case entirely — formed by the maxilla, which in two cases even 

 protrudes into the fossa. In the upper region the lacrymal 

 advances on the face, so that tbe fronto-maxillary suture is either 

 very limited, or in two cases- — B. TiypoxantJius, Leyden ; B. 

 araclmoides, Br. M. No. 43.10.12.2 (PI. XII. fig. 1)— a "lacrymo- 

 nasal suture is present. 



CallitJirix. 



Sixteen skulls examined. — The anterior margin of the lacrymal 

 fossa is always bordered by the maxilla, at least on its lower half 

 (PI. XII, fig. 7), and sometimes (C donacopJiila) on its whole 

 extension. The antero-superior angle of the lacrymal protrudes 

 forwards, least of all in C. donacophila, which therefore exhibits a 

 very broad fronto-maxillary suture ; in all the other species there is 



^ Op. cit. p. 175, fig. II B. 



^ Gr. Fischer, Anatomie der Maki, p. 90 (1804). 



