296 PHYSIOLOGICAL SERIES. 



In addition to the lateral sulcus there is an extremely 

 well-developed entolateral sulcus, as in Oilolm-nn* and 

 Otaria; its position and extent support the contention that 

 the lateral sulcus in Phoca really represents both the hit mil 

 and the entolateral sulci of these other Pinnipeds. 



The dorsal part of the crucial sulcus is much more 

 extensive than it is in P/toca, and the small precrucial 

 placed upon the dorsal surface. Hence the small "Ursine 

 lozenge" occupies a more usual position than it doe> in 

 Phoca. [It is only right to mention that by Phont I refer 

 more especially to the individual specimen upon which tin- 

 above description is based.] 



The intercalary and calcarine sulci are joined. 



According to Fish, the posterior cornu of the lateral 

 ventricle is smaller in Monachus than it is in Phoca. 



0. C. 1325 v ,/. 



P. A. Fish, Journ. Comp. Neurology, 1898, p. 81. 



D. 381. A cast of the cranial cavity of a Sea-Leopard (Steno- 

 rhynchus leptonyx). 



D. 382. The brain of a young Hooded Seal (Cystophora cristata). 



This brain exhibits the features of the basal surface in a 

 very distinct manner. Note especially the acute flexure of 

 the pyriform lobe, which produces a deep transverse valh>- 

 cula Sylvii. 



Note also the large, expanded, and highly complex floc- 

 cular lobes. 



The olivary bodies may also be seen cropping out at the 

 lateral edges of the pyramids. 0. C. 1325 v. 



D. 383. The brain of a Hooded Seal (CystopJwra cristata). 



This brain closely resembles that of the Monk Sea! 

 (D. 380), excepting that the calcarine sulcus does not join 

 the intercalary but overlaps it obliquely, as in Phoca. 



As in all Pinnipedia, there is a well-developed " U/ 

 lozenge " of Mivart. 0. C. 13:.' 



D. 384. The brain of a Hooded Seal (Cystophora cristata), 



In this excellent specimen the features of the brain 

 described in the other examples are shown with 

 clearness. 



