1888.} 



VISCERAL ANATOMY OF BIRDS. 



253 



In the very complete description of the respiratory apparatus of 

 birds which Prof. Wiedersheim gives in his ' Lehrbuch der ver- 

 gleichenden Anatomic ' there is no mention of any other bird in 

 which muscular fibres cover the obhque septum ; Prof. Huxley's 

 statement about the Duck is referred to in a footnote '. 



I have found that an identical structure occurs iu two species of 

 Penguin, viz. Eudyptula minor and Spheniscus demersus ; in both of 

 these birds the oblique septum is covered posteriorly by a layer of 

 muscular fibres which rise from the pubis and are attached ventrally 

 to the sternum. 



After referring to the late Prof. Morrison Watson's elaborate 



Fig. 1. 



Dissection of Fratercula arclioa, to illustrate disposition of oblique septum. 

 a, oblique septum ; /, coils of intestine ; Pb, pubis. 



and well-illustrated Report upon the Penguins collected by the 

 ' Challenger ' ^, and finding there no mention of this muscular layer, 

 I believed that this particular resemblance between the Pufiin and 

 the Penguins would be recorded for the first time in the present 

 paper. Quite recently I have become acquainted with the contents 

 of a short paper ^ by M. Filhol, in which he describes this muscular 

 layer in the Penguin, though in another species. The following 



1 P. 665, note 2. ^ gool. ChaU. Exp. vol. vii. 



3 " Sur la constitution du diaphragme des Eudyptes," Bull. Soc. Philom. (7) 

 t. vi. p. 235. 



