346 



PHYSIOLOGICAL SERIES. 



fedkires. In one specimen of Manatee (specimen D. 507), 

 however, I have seen a peculiar large tubercle of inverted 

 hippocampus such as I have found elsewhere only in tin- 

 primitive brain of Orycteropus and in the Prim:it< -. 

 Strange to relate, this condition was present in only one of 

 three Manatees' brains examined. 



The corpus callosum is peculiarly short and small, but it 

 has an extraordinarily complete genu (fig. 199). 



Sometimes there is a deep " splenial " (conjoint ral- 

 carine and intercalary) sulcus, in other cases only one or 

 two shallow furrows take its place. 



Fig. 200. (xf.) 



PSEUDO SYL.F. 



PLDC 



LAT. VENT. 



HIP 



-CORP. QUAD. 



HJQC. F 



The left half of a Manatee's brain, in which the roof of the lateral 

 ventricle has been removed by horizontal section. 



The base of the brain is quite typical, which one would 

 hardly gather from Murie's representation of it. T 

 are small optic tracts, prominent exposed crura << Trim", a 

 largo interpedunrnlar body, very prominent puns, tra- 

 pezium, and pyramids, and very large fifth, seventh, and 

 eighth nerves. Contrary to the statements of Murie, these 

 nerves are found in the positions usual in other Mammal.-. 



