242 THE MERYCOIDODONTID^E 



and much heavier posteriorly; the parastyles and mesostyles are more prominent; the inferior 

 caniniform premolar is somewhat reduced and more nearly approximates in size the true canine; and 

 the molars occupy proportionally more and the premolars proportionally less of the dental length. 

 Cope (1884B, p. 547) believed that the external nares were superior in position. I cannot 

 quite see this, except in so far as this feature is more apparent than real, because of the characteristi- 

 cally depressed skull. Cope thought that highly placed nares were an "indication of an aquatic habit 

 of life, such as is led by the hippopotamus." He continues: 



Like that animal, the nostrils in Cycloftdim were probably valvular to prevent the ingress of the water. The 

 animals probably passed much of their time in the water, and the nostrils could be brought to the surface for the 

 purpose of respiration, while the remainder of the head and body remained concealed. The prominent rim of the 

 auditory meatus suggests a similar valvular closure of the organ of hearing, and is also a provision for its easy 

 approximation to the surface of the water when necessary. 



As is apparent from the above, Cope considered these animals to be good swimmers, spending 

 much of the time in the water and only coming on shore for feeding and sleeping. I believe, on 

 the contrary, judging from the known skeletal material, that they spent most of their time on land 

 but that they probably did swim or take to the water occasionally, perhaps as a method of preserva- 

 tion, since they were so poorly provided with adequate means of defense against enemies. 



An interpretation of the relatively huge facial vacuities is difficult. Cope suggested that per- 

 haps they "supported an inflatable bladder like that of the crested seal, or a swollen muzzle like 

 that of the saiga antelope." Among living animals we find facial vacuities in the muntjac, the 

 Chinese water deer, the caribou, the Virginia deer, the llama, and others, but they are far less exten- 

 sively developed in proportion to size of skull. By inference, they may have had some connection 

 with large nasal diverticuli, which in most of the merycoidodonts lay in the lacrimal fossa. 



Etymology: Cyclofidius (round-eyed); Brachymeryx (short + ruminant); Pithecistes 

 (small ape). 



Species: 



C. calif omicus (Stock) 1930. 



C. densus (Loomis) 1925. 



C. lullianus Thorpe 1921. 



C. simus Cope 1878. Genotype. 



Species Probably Synonymous With C. simus: 

 C. brevifacies (Cope) 1878. 

 C. decedens (Cope) 1 884. 

 C. emydinus Cope 1884. 

 C. heterodon Cope 1878. 

 C. incisivus Scott 1 893. 



Cyclopidius californicus (Stock) 1930 

 PL XXXVII, figs. 1-5 



Original Reference: Oreodonts from the Sespe deposits of South Mountain, Ventura County, California. 

 Carnegie Inst. Wash. Publ. No. 404, pp. 38-39, pi. 2 (Leftaucheriw ? (Sespia) calif ornica). 



Type Locality: Lower Santa Clara Valley, near Santa Paula, Calif. Univ. Calif. Coll. Loc. No. 7305 

 NE. J4, Sec. 18, T. 3 N., R. 20 W., San Bernardino Base Line. Occurrence in canyon locally called Gas 

 Plant Canyon. Locality N. 3° E. of Gas Plant and N. 26° E. of Santa Paula well no. 16. 



Geologic Horizon: Lower Miocene (upper Sespe). Collected in a division composed of red, green, and 

 gray sandstone and of maroon sandy shale, about 2000 feet below the top of the Sespe formation. 



Type: Holotype, Cat. No. 27720 U.C.M., facial and palatal portions of skull and parts of horizontal rami. 



