92 



OSJTEOLOGICAL GALLERY. 



[Case 14.] The Pigs, which occupy Case 14, have long narrow skulls, 

 tuberculated molars, large curved canines, and four-toed feet, the 

 bones of all the toes being separate, and not united to form a 

 cannon bone. The dental formula of the Common Pig is I. f , 

 C. ^, Pm. 4:, M. x 2 = 44, giving the same number and distri- 

 bution of teeth as in the majority of Mammals of the earlier 

 Tertiary periods, but which is now found only in the genus Sus 

 and two genera of Insectivora. 



Skeletons are exhibited of a Wild Boar (Susscrofd), Wart-hog 

 (Phacochcems) , and Peccary (Dicotyles) ; and skulls, among others, 

 of the Pygmy Hog (Sus salvanius), Babirusa (B. alfurus), and 

 River-Hogs (Potamochcerus). There is also (Div. F) an interesting 

 series of upper jaws of Wart-Hogs, showing the variation they 

 present in the presence or absence of the small upper incisor teeth. 



The Ruminant Artiodactyles have molar teeth with crescentic 

 ridges. Their division into the Tylopoda, Tragulina, and Pecora 

 has been already noted, p. 40. 



The Tylopoda, or Camel tribe, differ from the other Ruminants 

 in the presence of a pair of small incisor teeth in the upper jaw, in 

 the absolute suppression of the outer toes, and in their having no 

 horns in either sex. 



The Camels are represented in Case 15 by a skeleton of the 

 Dromedary or one-humped species (Camelus dromedarius) and by 

 skulls both of that species and of the true or two-humped Camel 

 (C. bactrianus). Of the Llamas, there is a skeleton of the Llama 

 (Lama glama), which shows the close affinity of these animals to 

 the Camels, the skeleton and skull being merely smaller forms of 

 the same type. 



[Case 15.] The Tragulina (Div. E), containing the Common and Water 

 Chevrotains, are distinguished by the long canine teeth of the 

 males, by the shape of the "odontoid" process of the second 

 vertebra, which is conical, by the presence of four complete digits 

 to all the feet, all the bones of the leg being likewise fully de- 

 veloped, and by the spongy structure of the auditory bullse. 



The Pecora are characterized osteologically by the development 

 of horns in the majority of the species, at least in the male sex, 

 by the total absence of upper incisors, by their crescent-shaped 

 odontoid processes, rudimentary or absent outer digits, incomplete 

 fibulae, and simple inflated auditory bullas. 



