VIKWS oi" NATIMK • < »NTU AS ri;i •. U* 



uiiir wolves jiiid «lo^s. Hui a considoratioii of their anat- 

 omy — that is. of tlicir luaiu, skull and its snvcral parts, the 

 hyoid aj.paratns. llic ])clvis. the bones of the feet, and 

 the htarl — in fact, all the parts of their organization — 

 forees ns to reeo^Mii/.e that external form is of very little 

 eonse(juenee in the appreciation of the relations of the ani- 

 mals, and that we arc not only justified, but eomi)elled, if 

 we wouhl express nature, to brintr them ton;ether and keep 

 them as the constituent*; of one natural ^roup in contra- 

 distinction to all the other groups that are represented by 

 forms which have a similar external appearance. 



1 need only remind you that every one now recognizes 

 the bats as animals. 



In brief, then, mammals may be described as animals 

 which have no gills, which breathe by means of lungs, 

 have a quadrilocular heart, sending the blood to the 

 lungs, and receiving it thence and returning it to the rest 

 of the body ; a skull which has two condyles for articu- 

 lation with the vertebral column and which has all its 

 bones connected by siiture with or contained in the brain 

 case, except the lowei- jaw ; and the lower jaw itself is com- 

 prised of simple branches which articulate directly with 

 the brain case; the inner ear has three principal ear bones; 

 the females are viviparous and the emltryo developed from 

 a very small egg. 



In contrast, fishes can be characterized as animals which 

 are branchiate or l)reath by means of gills, whose heart is 

 bilocular, sending from one of its chambers the blood to the 

 gills to be there aerated by contact with the water, which 

 contains oxygen, an<l thence to the remaining portions of 

 the body, to be in turn taken by the other cavity of the 

 heart: the skull has an impaired median and circular 

 articulation for the vertebral column ; the upi»er jaw, pala- 

 tine, and other bones are free from the brain case, and inter- 

 vening between it and tlie lower jaw is a suspensorium of 

 well-developed bones ; the lower jaw is composed of several 

 pieces; the females are oviparous or ovoviviparous. 



