86 ME. W. G. ETDEWOOD OK THE HTOBEATS'CHIAL 



the homologies of the muscles of Xenopus with those of other 

 Anura will apply in the present case, and need not he repeated. 

 The most important feature in which the laryngeal musculature 

 of Fipa differs from that of Xenopus is in the absence of the 

 geniohyoideus internus. Arising from the roof of the larynx in 

 the elliptical area marked a in fig. 5, PI. 10, is a very loose tissue, 

 mainly connectire tissue, but containing numerous scattered 

 muscle-fibres which are inserted into the mucous membrane of the 

 pharynx behind the glottis. No particular direction can be 

 ascribed to the fibres, for they cross one another in a most irregular 

 manner. Eadiating outwards and backwards from the postero- 

 external border of the same area are a few muscle-fibres arranged 

 in the form of a thin sheet, attached distally to the internal 

 concave edge of the great wing of the hyobranchial skeleton. 

 Neither of these tracts appears to be of sufficient importance to 

 warrant the application of a distinctive name. 



The dilator laryngis (PI. 10. figs. 5 & 6, d) [Laryngeus proprius, 

 Mayer, 25. p. 538 ; Dilatator aditus laryngis, or Erweiterer, Henle, 

 19. p. 26, and Taf. 2. figs. 14, 15, & 23, m] arises from the 

 postero-external border of the laryngeal complex, and, considering 

 the large size of the muscle, its posterior attachment is remark- 

 ably small. It occurs partly on the dorsal and partly on the 

 ventral surface of the larynx. Its belly is large and well defined, 

 and narrows considerably anteriorly, and it is inserted by a small 

 tendinous extremity into the most external part of the lateral 

 promontory of the arytenoid cartilage (PL 9. fig. 2, d). The 

 dilator laryngis anterior (PI. 10. fig. 5, d.a.) is very clearly dis- 

 tinguishable from the dilator. It arises from the fascia of the 

 external surface of the anterior part of the latter muscle, passes 

 upwards, forwards, and inwards, and gradually diminishes in 

 width. It runs dorsal to the compressor (c) and is inserted into 

 the edge of the arytenoid cartilage guarding the side of the 

 glottis. A few of the fibres, also, are attached indirectly to the 

 arytenoid cartilage by being inserted into the aponeurosis between 

 the anterior and posterior bellies of the compressor. 



Compressor glottidis (PI. 10. fig. 5, c) [Compressor laryngis, 

 Henle, 19. Taf. 2. figs. 14, 15, p']. — The anterior and posterior 

 bellies of this muscle are very sharply difEerentiated, and the 

 aponeurosis between the two extends obliquely backwards and 

 outwards, exactly as in Xenopus. The aponeurosis is attached 

 by its ventral surface to the anterior edge of the lateral pro- 



