VIKWS OF NATURK CONTKASTKH. 16 



sont.uivt> ill part in the car honrsof tho cetaceous as of all 

 otiier maininals. 



Tluis wc lind tlio same bones subscrvii.'iit lu very diUcr- 

 «nt functions in the two types: in the mammal to hearinp^ : in 

 tho lisii servinLi ehiolly for the -connection of parts. The 

 statement may evoke your skepticism, but I must ask you 

 to accept it on trust, for time will not allow mc to demon- 

 strate its truth. [ can only pledge myself that it has, I 

 think, been clearly demonstrated that such is the case by 

 the study of the comparative structure, and development of 

 many forms, and by the collation of data derived from 

 various types consecutively considered. 



Connected with the skull you will perceive certain other 

 bones or appendages. In the cetacean you may see pendant 

 from the skull the articulation for the lower jaw, an appar- 

 atus composed of three bones on each side connected by a 

 central one, reminding one somewhat of a pair of hooks or a 

 card-rack. These bones arc known as the hyoid. In the fish 

 you will of course at once recognize the gills, which are on 

 four arches on each side, but observe also another arch in 

 front, and which performs the function of sustaining a 

 membrane attached to the gill covers. Further observe 

 that all these arches arise from a median row of bones to 

 which the tongue is attached in front. Let me recall now 

 a fact which you have doubtless heard of before — that even 

 man as well as all other mammals have gillcts in the foetal 

 stage of life, and of such gills the hj'^oid bones are the modi- 

 fied vestiges and reminders, and they roughly represent the 

 gills and appendages which are developed so largely in tho 

 fishes. 



Please direct your attention now to tho organs which serve 

 for the aeration of the blood in the cetacean, and to that which 

 corresponds in the fish. You will notice that in the for- 

 mer there are lungs on each side, as well developed and as 

 obviously lung-like as those of man, and that they arc con- 

 nected with the mouth by a tracheal tube which has an- 

 teriorly a thyroid apparatus, also as in man. On the other 

 hand in the salmon there is nothing like a lung, but in its 



