306 



COMPARATIVE ANATOMY 



cartilaginous auditory passage, with which it is continuous. In its 

 formation and farther development, the dermal musculature 

 primarily plays the most important part. 



In the higher Mammals the pinna and the cartilaginous part of 



s. 



FIG. 225. THE PINNA OF VAKIOUS PRIMATES. 



In A, the shaded portion (b) represents the zone of the auditory eminences of the 

 embryo, the unshaded that of the later-formed auditory fold. B, Man, 

 Baboon and Ox, drawn to the same scale and superposed : .s-', s", s, spina or 

 tip of the ear. C, Macacus rhesus, with upwardly directed tip ; and D, Cerco- 

 pithecus, with backwardly directed tip. E, Man : the muscles are indicated 

 as follows m.a, attolens auricula?; m.a', antitragicus ; m.t, tragicus ; 

 m.t', inconstant muscle, extending from the tragicus to the margin of the 

 helix ; m.h', helicis major; m.h", helicis minor ; s, tip of the ear rolled over. 



A-D, after Schwalbe ; E, after Henle. 



the external meatus (here also continuous with one another) arise 

 from a series of rounded eminences on the first and second visceral 



