Anatomical Structure of certain of the Cetacea. 413 



sion of the teeth as in most of the Mammalia. The crania of 

 two foetuses of the narwhale now before me show no such appear- 

 ances. On each side of the upper jaw, and in the usual place, 

 there are two hollow teeth, obviously the extremities of the 

 spiral permanent tooth of the male. These teeth are complete- 

 ly imbedded in the jaw in the young narwhale ; observation tells 

 us, that if the animal be a male the left tooth continues to grow, 

 the right, after a time, fills up, its central cavity for containing 

 the pulp disappears, and, after attaining a growth of 5 or 6 

 inches, the jaw elongates, to correspond with the growth of the 

 animal and of the other tooth, and the aborted tooth remains 

 imbedded in the jaw for life. 



Digestive Organs *. 



Inquiries into this system of organs are by no means so com- 

 plete as they ought to be. My own very limited field of inquiry 

 has presented but few novel facts, if any ; but I feel inclined to 

 view differently from those who have preceded me in this in- 

 quiry, that structure in the second stomach of the porpoise and 

 dolphin, which many have considered as glandular merely. 

 That it bears a considerable resemblance to the tubular portion 

 of the kidney of some animals cannot be overlooked, but this, for 

 obvious reasons, does not seem to remove the difficulty we have 

 in considering the whole structure as merely glandular. The 

 i .'. . . (. 



* I have not observed the muscles in any of the whale tribe or Cetacea to stiffen, 

 nor the blood to coagulate after death. Others, however, whose opportunities for 

 observation may have been more extensive, may have noticed these phenomena. 

 The muscles are, compared with other Mammalia, soft and easily lacerated. The 

 anterior filaments of the spinal nerves are greatly more numerous or larger than the 

 posterior.- 



SF 2 



