SUBORDER D 



ARTIODACTYLA 



197 



incisor tooth. The cheek teeth are brachyodont, with several roots ; the 

 crowns are covered with thick wrinkled enamel, and as a rule there is a basal 

 pillar between the internal crescents above and the external crescents below. 

 The ectoloph of the superior molars always exhibits two vertical folds, 

 parastyle and mesostyle. Between each external cusp and its corresponding 

 inner crescent there is a pit which shows spur-like processes beginning 

 at the posterior end of that crescent. The superior premolars are very short, 

 and give the impression of being half molars, yet the inner cone does not 

 assume its position through the deformity of a true internal tubercle but 

 through the bending round of the 

 edge of the tooth. The inferior 



molars are low and typically seleno- !• *\% _ ll'l 



dont ; the premolai-s are slightly 

 elongated and consist of two very 

 unequal segments, a shorter posterior 

 one and a longer anterior one. In 

 the oldest fossil forms there are four 



Polyeladus dicranius Nesti. Upper Pliocene, Val 

 d'Amo, Tuscany. A, Tnree premolars and first 

 molar of upper jaw. B, Same teeth of lower 

 jaw. Vi- 



Fig. 273. 



Cervus elaphiis Linn. 

 Recent. Tarsus and up- 

 per end of metatarsus, a, 

 Astragalus ; c, calcaneum ; 



Proximal pieces of the C'i, cuneiform ; cb, cuboid ; 



lateral metacarpals; B, mill., viIV., third and 



radius. 1/7- (After fourth metacarpals, 1/3. 



Flower.) (After Flower.) 



Cervus elaphus Linn. 

 Recent. Plesiometacar- 

 pal fore - foot, trfi, to5, 



premolars present ; otherwise there are but three. The posterior upper milk 

 cheek tooth corresponds exactly to the true molars ; the two anterior teeth 

 have the elements of the molars, but the internal crescents are somewhat 

 incomplete. The last inferior milk cheek tooth is three -lobed ; the two 

 anterior ones are nearly like the teeth replacing them. 



In the carpus (Fig. 272) the magnum and trapezoid are co-ossified. The 

 median metacarpals are early united into a cannon bone, the lateral meta- 

 carpals are exceedingly attenuated, generally rudimentary, sometimes the 

 proximal portions only {Plesiometacarpi), sometimes the distal ends only 

 (Teleometacarpi), being developed as styloid vestiges. All true deer possess 

 short lateral digits, but these are absent in the giraffe. In the tarsus, as 

 a rule, the cuboid and navicular are united (Fig. 273), as are also the second 

 and third cuneiform bones. The small first cuneiform is always distinct. 

 The lateral metatarsals are present either as short distinct proximal ends, 

 or these may also be firmly co-ossified with the cannon bone. Lateral digits 



