582 



CETACEA. 



Fig. 270. 



A section of one of the lobes or renules of the kidney 

 of a Dolphin. 



The Nervous System. The nervous system, 

 like the greater part of the other organic sys- 

 tems, has in many species of the Cetacea been 

 the subject only of superficial observations. 

 Formed on the plan of that of Mammalia in 

 general, it has followed in its deve- 

 lopment that of the other organs, in 

 all cases in which it was naturally de- 

 pendent on such modifications. Thus 

 the lumbar and sacral nerves do not 

 give origin to those of abdominal 

 members, whilst, on the other hand, 

 the coccygeal nerves are found nume- 

 rous and powerful. The olfactory 

 nerves do not exist, unless, as some 

 authors say, it is in the form of almost 

 imperceptible threads. What appears 

 certain is, that in the common Dol- 

 phin, and in the common Porpesse 

 there are no traces of ethmo'idal 

 openings ; and if there are holes in 

 the ethmoid of the Whale, they are 

 in very small number, and nothing 

 proves that they give passage to 

 nerves.* In the common Dolphin 

 and Porpesse, the brain is found as 

 richly developed as in any Mammi- 

 ferous quadruped whatever. 



Fig. 271. 



To judge from the capaciousness of the 

 skull, the other species of this family of Cetacea 

 have not been less liberally gifted than the 

 common Dolphin. The brain of the Cachalots 

 and the Whales has not been made a subject 

 of study, or has been so only in a very super- 

 ficial way. To judge of it by the cranial 

 cavity, one may conclude that in them this 

 organ is reduced to very small dimensions. 



[The illustrations of the brain of the Cetacea 

 (Jig. 271, 272, 273) are taken from the ex- 

 cellent figures of the brain of the Dolphin 

 (Drtphinus Delphi-:), published byTiedemann 

 in the second volume of his Zeitaclirift fitr 

 Physiologic, (pi. jai. p. 251.) The following 

 description embodies the observations of the 

 same author on the brain of the Dolphin, and 

 of Hunter on that of the Ealtenoptera (Piked 

 Whale). In a young specimen of the Baltena 

 rostruta, which measured seventeen feet, Hunter 



Fig. 272. 



Brain of the Dolphin, Delphinus Delphis, 



* M. F. Cuvier seems here to have overlooked the 

 fact that Hunter had established the existence of 

 an organ of smell in the Balaenidce. He observes, 



Base of the brain of a Dolphin, Delphinus Delphii. 



found that the brain weighed four 

 pounds eight ounces. In a young 

 Baltrna mysticetus nineteen feet 

 long, Scoresby found the weight of 

 the brain to be three pounds twelve 

 ounces. From analogy we may 

 suppose that the brain had here 

 acquired nearly its full development, 

 which gives us, taking the weight 

 of the full grown whale at 11,200 

 pounds, the ratio of the weight of 

 the brain to that of the body as 

 sfjLj. In the smaller Cetacea, 

 however, the brain is not dimi- 

 nished to a proportionate size, but 

 exhibits a development which may 

 be said to be extraordinary, even 

 in the Dolphin of six feet in 

 length. 



In tracing the brain according to 

 Tiedemann's method from below 

 upwards, we first observe the 



" In many of this (the Whale) tribe, there is no 

 organ of smell at all ; and in those which have 

 such an organ, it is not that of a Fish, therefore 



