430 DR. J. E. GRAY ON THE BRADYPODID.B. [May 2, 



occasions it used to utter a shrill sound, like a Monkey ; but I have 

 never, on any other occasion, heard it uttering this sound. 

 " Hoping that some of these notes may be of service to you, 



" I remain, &c, 



"Berthold Seemann. 

 " 4 Westminster Chambers, Victoria Street, 

 "April 1, 1871." 



In this paper I have adopted the three genera proposed by me in 

 the paper on the Skulls of the Family in the Proc. Zool. Soc. 

 1849, and the nomenclature used in the 'Catalogue of Carnivorous, 

 Pachydermatous, and Edentate Mammalia in the British Museum,' 

 1869, p. 362. 



Tribe I. Cholcepina. 



The hands with two claws, the feet three-clawed. Skull large, 

 ventricose ; front edge of the lower jaw much produced, into a spoon- 

 like central lobe. Intermaxillary bones well developed, forming an 

 arched edge to the front of the upper jaw. The front grinders in 

 each jaw elongate, acute, working against each other like the canines 

 of a Boar, the upper one being over the front of the lower one, and 

 separated from the other grinders by a considerable vacant space. 

 The angle of the lower jaw is thick, rounded, and only slightly pro- 

 duced, scarcely exceeding the back edge of the condyle ; the front 

 upper grinder placed quite close to the front end of the bone, and at 

 a distance from the other teeth, which is the largest tooth. It is 

 well developed and of a triangular shape in the skulls of very young 

 animals, and separated from the other grinders by a considerable 

 space in both jaws. It becomes much developed by age ; and a large 

 cavity is formed behind the tooth in the upper jaw for the reception 

 of the one in the lower jaw. The malar bone short, triangular, and 

 dilated at the end, with a short, narrow, horizontal upper process, 

 and a broad or descending one. 



In the young skull the nasal bone is small, elongate, triangular, 

 projecting in front of the suture of the frontals. This bone is well 

 figured in Rapp's ' Edentata,' t. iii. f. 2, 3, and is to be seen more 

 or less distinctly anchylosed in some of the adult skulls ; and the 

 anterior process on the lower jaw is narrow. The intermaxillaries 

 are separated from the maxillae and from each other by narrow 

 sutures, which are obliterated in the adults. The malar bone is elon- 

 gate, produced horizontally, with a short upper rounded process and 

 a much larger acute angular process, which is obliquely produced 

 posteriorly. The skulls of the young specimens showing the sutures 

 are as short and broad as in the more adult ones, except in one case 

 (736c), where it is not above two-thirds the width; but only the 

 front part of the jaws exist of this specimen, while there are two or 

 three of different ages showing the sutures. 



A very young skull, with a broad nose showing all the sutures, 

 and having the nasal bone well produced, is figured by Rapp in his 

 ' Edentata,' t. iii. f. 2, 3, as Bradypus didactylus. 



The temporal muscles occupy a very different space in the series 



