ENDOCRANIAL ANATOMY OF OREODON 273 



A short preliminary report has ah'eady been made with this in 

 view (S) though at that time but two of the specimens had been 

 examined in detail. 



Moodie {22, fig. 14) has figured a ventral view of an endo- 

 cranial cast of Merycoidodon culbertsonii, Leidy, in connection 

 with his annotations on the subject of Tertiary mammalian brain 

 casts. His specimen was evidently very badly weathered. 

 Outline drawings of the endocranial cast of an oreodont, Meryco- 

 choerus, have also been published by this author (^3, figs. 2 and 

 3). No description, however, is given of this cast and his ter- 

 minology in labeling the endocranial detail in the figures is diffi- 

 cult to interpret. 



In the introduction of his earlier publication this author makes 

 the following statement with regard to brain casts in general: 

 ''The cast in either case" (reptiles or mammals) ''is of the dural 

 cavity and gives only an approxunate picture of the actual con- 

 figuration of the brain of the animal, whether reptile or mam- 

 mal, since the smaller convolutions make no impression of the 

 inner surface of the skull, even in man" {22, p. 136). This 

 statement seems to have been made on the strength of Scott's 

 earlier work {21) but does not at all coincide with my own obser- 

 vations. ^ 



In order to be sure how much information about the morphol- 

 ogy of the brain of fossil mammals might safely be deduced from 

 a study of endocranial casts, I undertook some years ago to make 

 a series of endodural, endocranial and encephalic casts of recent 

 forms for comparison. A considerable number of such casts 

 were prepared, the material used being chiefly Canis familiaris 

 and Felis domestica but other material was also employed (Ovis, 

 Sus, Bos, Viverra, Putorius, etc.). 



As a result of these comparisons it became quite evident that 

 in the adult annuals investigated, practically all the details of 

 the pattern of the lateral convex surface of the cerebrum were 



2 With reference to this question Elliot Smith {12, q. v.) pointed out long ago 

 that accurate information concerning the brain could be gleaned from the study 

 of casts of the cranial cavity in the case of most of the lower gyrencephalous 

 mammals. 



