No. I.] THE VERTEBRATE EAR. 22/ 



deep-seated, i.e. thoroughly protected, organs are subjected to 

 destructive changes in most unaccountable manner in correla- 

 tion with changes affecting concomitantly all other parts of 

 the body in greater or less degree. I must admit that it is by 

 no means clear to me what has been the gain to mammals in 

 changing from the sauropsid to the mammalian type of cochlear 

 organ, for I can see no physical reasons why the reptilian organ 

 should in great part be destroyed after having once acquired 

 the degree of development it had attained in the immediate 

 ancestors of the mammals and birds, as illustrated by the con- 

 dition present in such a reptile as the Alligator. 



Having found from my own investigations in three groups of 

 birds, Rasores (Gallus), Columbinse (Columba), and Passeres 

 (Mimus), that the development of the cochlea is not so far ad- 

 vanced as in the hydrosaurian reptilia, it will be necessary to 

 change the view advocated by Hasse, according to which the 

 saurian reptilia stand as transitional forms between the am- 

 phibia and the lower reptilia and the birds, for it is obvious 

 that in cochlear anatomy the birds hold a place apart from the 

 direct line of descent as typified in the mammalian cochlea. As 

 this is a matter of great importance, not alone as concerns the 

 ear, but for the general problem of the phylogeny of the avian 

 group as well, I quote the following account which our author 

 gives of his views of the phylogenetic relationship of birds to 

 reptiles as shown in the quotation from page 35 of his final 

 digest of auditory anatomy. 



" Das Gehororgan der Crocodile bildet nun den unmittelbar- 

 sten Uebergang zu dem der Vogel, wie das von Siredon den 

 schonsten Uebergang von den Fischen, namentlich den Teleo- 

 stiern, zu dem der Amphibien zeigt und die Aehnlichkeit, 

 namentUch in dem wichtigen Bestandtheile der Schnecke, ist 

 so gross, wie sonst nirgends zwischen zwei Wirbelthierclassen, 

 mit Ausnahme vielleicht zwischen Vogeln und Monotremen, 

 welche letztere zu untersuchen ich leider keine Gelegenheit 

 hatte. Ich finde, wie das uberhaupt aus dem Verhalten der 

 iibrigen Organe bei den Vogeln zu erwarten, im Ganzen nur 

 geringfugige Unterschiede in der Gestalt des hautigen Laby- 

 rinthes, die sich wohl dahin pracisiren lassen, das diejenigen 

 Vogel, welche ein ofBnes foramen rotundum besitzen (Natatores), 

 also diejenigen, die wir als tiefer stehend erkannt haben, eine 



