158 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



Order UN GU LATA. 



HOOFED ANIMALS. 



Teeth heterodont and diphyodont. Crowns of molars broad with 

 tuberculated or ridged surfaces. No clavicles. Toes with blunt, 

 broad nails, or in the majority of cases with hoofs, more or less m- 

 closing the ungual phalanges. The testes descend into a scrotum. 

 There is never an os penis. The uterus is bicornuate. The mammae 

 are usually few and inguinal, or may be numerous and abdominal (as 

 in Suina), but are never solely pectoral. The cerebral hemispheres 

 in existing ungulates are well convoluted. {Flower and Lydekker, 

 abridged.*) 



Suborder ARTIODACTYLA. 



ARTIODACTYLES. 



Premolar and molar teeth usually not alike, the former being 

 single and the latter two-lobed. Last lower molar of both first and 

 second dentition almost invariably three-lobed: and the first tooth 

 of the upper cheek series always without a milk-predecessor. Nasal 

 bones not expanded posteriorly. Dorsal and lumbar vertebras to- 

 gether always nineteen, though the former may vary from twelve to 

 fifteen. Third and fourth digits of both feet almost equally de- 

 veloped. Stomach almost always more or less complex. Colon con- 

 voluted. Cfecum small. Mamma? few and inguinal, or numerous 

 and abdominal. {Flower and Lydekker, abridged.) 



Section STTINA. 

 PIG-LIKE ARTIODACTYLES. 



The existing members of this group are characterized by their bun- 

 odont molars and the absence of a complete fusion of the third and 

 fourth metapodials to form a " common bone." The full Eutherian 

 dentition is very frequently present. 



The existing swine-like animals may be divided naturally into 

 three families: I. Hippopotamidce ; II. Sind(v, or true pigs; III. 

 Dicotylidos, or peccaries. {Flower and Lydekker.) 



a The skeleton of a fossil elephant existed in the Papago well, Pozo Verde, 

 Sonera, Mexico. I obtained fragments of bone and one molar tooth, which 

 were sent to the U. S. National JIuseum In 1893, and identified by J. M. Gidley 

 as Elephas colombi Falcon. 



