ARTIODACTYLA. 757 
tarsals are fused in Zragulus, free in the other genus Dor- 
catherium ; the fibula is complete. There are no upper incisors, 
the upper canines are long and pointed, especially in the males ; 
the lower canines are like incisors; the dental formula is 
pee The Chevrotains ruminate, and the stomach is divided 
into three chambers, the many-plies being .rudimentary. The 
placenta is diffuse. The Chevrotains are often confusedly 
associated with the musk-deer (AZoschus), with which they have 
no special affinities. 
Species of Zragu/us (smallest among living Ungulates) occur in 
Indo-Malaya, India, and Ceylon; one species of Dorcatherdum, 
of aquatic pig-like habits, is found on the west coast of Africa. 
Group 4.— Pecora or Cctylophora — the true ruminants, including 
deer, giraffes, cattle, and sheep. Only the third and fourth 
Fic. 407.—Stomach of sheep.—From Leunis. 
a, Esophagus ; c, rumen or paunch; d, reticulum or honeycomb- 
bag ; ¢, psalterium or many-plies; 4, abomasum or reed ; 4, 
beginning of duodenum. 
digits are complete, the fused third and fourth metacarpals and 
metatarsals form ‘‘cannon bones.” In the embryos of ox and 
sheep, the second and fifth metacarpals and metatarsals are also 
represented; the second metacarpal and fifth metatarsal are 
unstable and soon disappear; small traces of the fifth metacarpal 
and second metatarsal persist. The fibula is represented by 2 
small nodular bone articulating with the lower end of the tibia, 
and forming the external malleolus. There may be in addition 
a rudiment of the proximal end attached to the upper part of 
the tibia, but the two parts are never united. Paired outgrowths 
of the frontal bones are common, capped with horny sheaths in 
the Bovide, deciduous and restricted to the males in almost 
all Cervide. There are no upper incisors, and rarely upper 
canines; there are three pairs of lower incisors, which bite 
against the hardened gum above ; and the lower canine resembles 
and is in the same series as the incisors; the typical dent’tion is 
= The stomach has four distinct compartments. The placenta 
