No. i.] OSTEOLOGY OF PCEBROTHERIUM. 21 



" Alle bisher angegebene Merkmale sind vielmehr durch die 

 Grosse als durch die Art des Thieres bedingt. Das einzige 

 auffallende Merkmal, wodurch sich die Tylopoden dann aller- 

 dings von den meisten Hufthieren unterscheiden wiirden. besteht 

 in der schiefen Stellung der Fissura coronalis, die von hinten 

 median, nach vorn lateral gerichtet ist." 



In PcebrotJierium the hemispheres are rather short and narrow, 

 ending posteriorly a little in advance of the auditory meatus and 

 tapering anteriorly, as in the brains of the smaller ungulates, 

 such as the tragulines, Moschus t etc. In the anterior part of 

 the hemispheres the vertical depth is conspicuously small. The 

 cerebellum is large and completely uncovered, the cerebrum not 

 extending over it at all. The frontal lobes of the hemispheres 

 are extremely small, while the parietal, occipital, and temporo- 

 sphenoidal lobes are fairly well developed. The cortex is much 

 less richly and complexly convoluted than in the camel and 

 llama, and the convolutions are but very slightly sinuous. The 

 sulci which are present are, with few exceptions, those which 

 Krueg has mentioned as being characteristic of all ungulates. 

 In general shape and appearance the brain of Moschus is very like 

 that of PcebrotJierium ; but there are important differences, espe- 

 cially in the degree of "pronation" and "supination" (to use 

 Krueg's terms). In Moschus, as in Tragulus, the hemispheres are 

 strongly supinated ; i.e. the sulci, which are typically confined to 

 the medial surface, make their appearance on the dorsal side. 

 In PcebrotJierium the opposite tendency is apparent ; viz. for the 

 sulci of the dorsal surface to move toward the middle line. The 

 fissura lateralis is thus brought close to the medial edge, from 

 which it is separated only by a very narrow median gyrus ; it is 

 long and nearly straight, and is closed in front by the union of 

 the median and medi-lateral gyri. An accessory sulcus runs 

 parallel with the lateral for about three-fourths of its length. 

 The suprasylvian sulcus is placed very high up, nearly, though 

 not quite so high as in the camel : it is very long and but slightly 

 sinuous, and anteriorly passes into the coronal sulcus. The latter, 

 if correctly identified, is placed higher than in the recent spe- 

 cies ; and its posterior limb runs inward and forward, almost 

 reaching the median line. The diagonal fissure, if present at 

 all, is represented by a very short sulcus which connects the 

 sylvian fissure at its anterior end with the suprasylvian. The 



