358 



occipltals are longer and the acoustic bullse are larger in proportion than in the Hare. The 

 squamosal has a similar form and relation to the tympanic mastoid to those in the Hare. 

 The inner termination of the auditory meatus forms a well-marked trumpet-mouthed expansion 

 within the tympanic bulla. The articular surface for the lower jaw has the form of a wide 

 groove scooped out longitudinally beneath the base of the zygomatic process. A depressed 

 plate is continued from the inner side of the glenoid cavity and from the contiguous under 

 and fore part of the squamosal forwards to the back part of the alveolar portion of the upper 

 jaw, circumscribing a space into which the ' foramen lacerum anterius ' opens, and analogous 

 to the interpterygoid canals of the Agouti. The basisphenoid, alisphenoids, and pterygoids 

 are wanting in this skull. The superorbital ridge has a small median notch, but not the 

 wide and deep posterior ones which are seen in the Hare. The chief difference which the 

 skull of the Dolichotis presents, as compared with that of the Leporidee, is seen in the enormous 

 size of the antorbital vacuity. The outer surface of the maxillary shows a large shallow 

 excavation in which project the bosses formed by the implanted extremities of the curved 

 molares. The nasal bones are long and broad. The nasal processes of the premaxillaries 

 extend as far back as the nasals. The ramus of the lower jaw has a thick ridge extending 

 along the outside of the alveoli, towards the condyle : the molar angle is compressed, much 

 produced backwards, and rounded at its extremity ; it is directly continued from the under 

 and hinder borders of the jaw. 



Presented by Sir Everard Home, Bart., V.P.R.S. 



Genus Hydrochcerus. 

 Dental formula : i j=|, p {^, m ^=20. 



1973. The skeleton of a young Capybara (Hydrochcerus Capybara). 



The vertebral formula is : /cervical, 13 dorsal, 6 lumbar, 2 sacral, and 8 caudal : but the 

 caudal series is incomplete in the present skeleton, and the first anchyloses with the two 

 normal sacrals in the adult. The transverse processes of the last cervical are perforated, like 

 those of the other six, by the vertebral arteries. Seven pairs of ribs articulate directly with 

 the sternum, which consists of six bones. Short metapophyses are developed from the five 

 anterior lumbars. There is no trace of clavicle. The acromion is long and slender, and bifid 

 at its extremity, with the longer division directed downwards or backwards. The humerus 

 is widely perforated between the condyles, but not above the inner condyle. The scaphoides 

 and lunare are connate in the carpus. The pollex is wanting in the fore feet, and both the 

 hallux and the fifth toe are wanting on the hind feet. 



Mus, South. 



1974. The skull of a full-grown Capybara (Hydrochoerus Capybara). 



Although the entire series of permanent teeth is in place, and this skull measures upwards 

 of seven inches in length, the sutures between the elements of the occipital bone still remain. 

 The compressed paroccipitals, developed as exogenous processes from the exoccipitals, are of 



