QUADRUPEDS. 211 



tion of very young narwals, can alone determine the truth 

 of this conjecture. 



B. Blow-hole single, without a bony septum. Teeth ill 

 the lower jaw. 



125. Physeter. Spermacete. No elevated fin on the 

 back. The Ph. 7nacrocej)]ialus and Catodon, are the twd 

 species which constitute this genus. 



126. TuRsio. A high dorsal fin. T. vulgaris and 

 microps, are recognised species, 



MARSUPIALIA. 



Uterus destitute of a placenta. 



In all the animals of this division, the uterus is complex, 

 such as has been already described *. The young at birth 

 are blind, and remain a long while dependent on the mo- 

 ther. They are either deposited in a ventral pouch con- 

 taining the teats, or they attach themselves to the mother 

 by their feet and tails. The ventral pouch and teats are 

 supported by two bones, which are attached to the os pubis, 

 and project along the abdomen, on the central side of the 

 teeth. In these, the muscles belonging to the pouch 

 and teats have their origin. These marsupial bones have 

 likewise peculiar muscles attached to them, for the regula- 

 tion of their o\vn motion on their joint at the pubis. The 

 scrotum of the male is placed in front of the penis. 



In general habits, the marsupial animals bear a near re- 

 semblance to the glires, although, in the arrangement of 

 their teeth, some of the genera approach the ferae. 



All the toes of the hmdr-feetfree. The uterus is double. 



* Vol. I. p. 39T. 



