ON THE UAKAEI MONKEYS. 123 



length ; with the lateral lobes it is altogether 1*25 inch transversely. 

 The flocculi are large, and the pons Varolii well developed. The medulla 

 has distinct olivary bodies. 



In the general characters of its brain, as will be thus seen, Brachyurus 

 approaches most nearly the genera Cebus and Piihecia (including Chiro- 

 potes), and especially the type found in Cebus apella. With Ateles and 

 Lagothricc it has no close relationship ; and the same may be said as 

 regards Mycetes ; it also departs widely in the greater complication and 

 development of the brain from Callithrix, Chrysoihrix, and the smaller 

 Cebidse generally. 



Eeviewing the facts already stated as to the structure of Brachyurus 

 rubicundus, it is evident that Brachyurus is a perfectly good genus, more 

 or less intimately related to a number of the larger Cebine forms, but 

 nevertheless characterized by a combination of characters peculiarly its 

 own. A relationship to Mycetes, suggested by its external appearance 

 and the form of the lower jaw, is not borne out by its visceral anatomy, 

 the brain and liver both pronouncing decisively against the idea, besides 

 other peculiarities. With Ateles and Lagothrioc it has no particular 

 features in common, but it undoubtedly approaches Cebus in the structure 

 of its brain ; and it is with this genus and Piihecia (including Chiropotes) 

 that it has probably the nearest affinities. 



The institution of a genus Ouakaria for the reception of these short- 

 tailed Monkeys by Dr. Gray (P. Z. S. 1849, p. 9) seems to me unneces- 

 sary. As he there remarks, the genus Brachyurus, as originally proposed 

 by Spix (Sim. et Vespert. Bras. p. 11), contained two species, B. israelita 

 (I. c. pi. vii.) and B. oualcary (pi. viii.). The former of these is now 

 generally referred to the genus Piihecia, standing as Piihecia chiropotes 

 (cf. Sclater, P. Z. S. 1871, p. 228). Having examined skulls of all the 

 known species o Brachyurus, as well as of Pithecia satanas, which is p 

 merely a representative form of P. chiropotes, I am unable to agree with 'p. 645. 

 Dr. Gray (I. c.) as to Spix " having evidently described the teeth &c. of 

 his first species in his generic character," for I find the characters there 

 given apply equally well to both the forms under consideration. Indeed, 

 as the " character essentialis " of the genus Brachyurus is " Cauda non 

 volubili, abbreviate^" B. israelita, in which that organ is of the normal 

 length, can in no way be considered the type of the genus. With certain 

 other points, too, of the " descriptio " there given, B. oualcary corresponds 

 better than the first species. I therefore agree with Isidore Geoffrey 

 (Exped. Am. Sud, Mammif . p. 18) in retaining the generic name Brachy- 

 urus, of which Oualcaria thus becomes a synonym *. 



* The name Brachyurus has also been used, but erroneously (cf. Sclater, 'Ibis,' 1877, 

 p. 260), for the Ant-Thrushes (Pitta). Mr. Alston ha?, since this paper was read,' 



