514 



PROCEEDINGS OF THE ACADEMY OF 



JIab. Brazil. 



General color yellowish brown, darker upon the occiput, upon the forehead 

 a few long black hairs, buttocks, region of the anus and inferior basal portion 

 of tail dark reddish brown. 



I had long suspected that the three species of this genus described by Isidore 

 St. Hilaire, were in reality one and the same species ; no specific characters art- 

 manifest in their coloration, or skulls, the different species being based upon the 

 development of the anterior thumbs, this member being absent in the arachnoides ; 

 replaced by a small nailless tubercle in the tubifer, and surmounted by a nail in 

 the hemidactylus. In the Magazin of Messrs, Verreaux, 9 Place Royale, Paris. 

 I found specimens having upon one hand the tubercle, and upon the other the 

 nailed thumb, others with the tubercle upon one hand, but absent upon the 

 other. Isidore St. Hilaire himself (Cat. de3 Primates, p. 51) expresses a doubt 

 as to whether the arachnoides and hemidactylus are really distinct. In Sep- 

 tember and October, 1860, I was unable to find the hemidactylus in the Paris 

 Museum, all the Brachyteles being labelled Eriodes arachnoides. 



Skull of No. 597, young, occiput broken Antro-posterior 3-8 ; occipitofron- 

 tal 3 ; bi-temporal 2 ; cranial capacity ? ; facial angle 66. 



Lower jaw. Angle to symphysis 2 ; angle to condyle 1-3 ; angle to coronoid 

 process 1-4 ; posterior molar to coronoid process -88. 



Genus III. LAGOTHRIX, Geoff. 



Lagothrix, Geoff., Ann. du Mns., vol. xix. 1812, p. 106. 

 Gastrimargus, Spix, Sim. et Vesp., 1823, p. 39. 



Caput obtusum, rotundatum ; rostro sima, manibus pentadactylis ; dentes 

 primores parvus, lanarii illio longioris. 



Body heavy, head globular, muzzle of adult much flattened, anterior hands 

 pentadactyl, incisors small and of unequal size, the superior median being 

 largest; canines very large and strong, carinated on their posterior surfaces, 

 and grooved anteriorly ; anterior nasal foramen nearly circular. 



This genus was founded by Geoffroy Sr. Hilaire, in his Tableau des Quadru- 

 manes (ante cit.) Spix, eleven years after, in his elephantine work upon the Quad- 

 rumana and Cheiroptera, of Brazil, proposed for it the name Gastrimargus, 

 from the great voracity of the only known species, which is said to exceed that 

 of any others of the American Quadrumana. The skull can be readily distin- 

 guished from that of the Sapajous and Brachyteles by the mode of articulation 

 of the nasal bones with the intermaxillaries. In the Sapajous no true articula- 

 tion can be said to take place, the intennaxiilaries terminating generally in a 

 point a short distance below the intermaxillaries, though sometimes barely 

 touching them ; in the Brachyteles aud Lagothrix, a broad, well-marked artic- 

 ulation takes place, ia the former species perpendicular to the suture between 

 the nasal bones, and in the latter parallel to it. The rami of the lower jaw are 

 much broader than in either of the before mentioned genera, approaching in 

 size and form those of the Howlers. 



Lagothrix hdmeoldtii, Geoff. 



Siraia cana, Eumb., Receuil des Obs., vol. i. 1811, p. 354. 



Simia lagothrica, " " " " pp. 322 and 354. 



[Nov. 



