SKELETOSr AND LARYNX OF XENOPFS AND PIPA. 89 



able size. It partially overlaps the dilator muscle and is inserted 

 into the dorsal surface of the larynx. In older specimens, how- 

 ever, the greater part of the muscle becomes transformed into a 

 fatty substance of a dark brown colour, similar to that which 

 occurs in abundance around the pointed cartilage at the front of 

 the hyobranchial skeleton and on the underside of the alse. Such 

 part of the muscle as remains unchanged is attached to the 

 postero-lateral corners of the laryngeal skeleton, in the position 

 already recorded for it by Mayer (25. p. 536) and Henle (19. 

 p. 26 and Taf. 2. figs. 14 and 23, 7'). At no age does the muscle 

 develop a tendinous extremity as it does in Xenopus. 



Male. 



For details of the laryngeal muscular system of the male Pipat 

 I have been obliged to rely entirely on the account given by 

 Oronberg, for both Mayer's and Henle's descriptions of these 

 muscles refer to the female, aud althougli I have had access to 

 three specimens of the male, they were all unsuitable for a care- 

 ful examination of their muscular anatomy. Gronberg describes 

 (18. p. 638) four intrinsic muscles of the larynx. For the muscle 

 around the glottis he accepts Henle's name Compressor : it 

 appears to correspond exactly with that muscle which, in the 

 female I liave called the compressor, so that it is unnecessary to 

 discuss it further. The other three, however, open up debatable 

 points. They arise from the sides, roof and floor * of the larynx, 

 and extend nearly its full length ; and their bellies are so united 

 tliat Gronberg confesses his inability to decide w^hether they are 

 three originally distinct muscles, or whether they are divisions of 

 the same muscle, its tendon having split into three. He elects to 

 adopt the former view. The tendon of the most dorsally-lying 

 muscle (18. Taf. 38. figs. 19 and 20, S 1)\^ attached to the arytenoid 

 cartilage guarding the glottis, and this muscle he identifies as the 

 " dilatator laryngis " of Rana. The tendon of the ventrally- 

 disposed muscle (18. figs. 18 and 20, S 3) runs to the external pro- 

 montory of the ossified part of the arytenoid, and the contraction 

 of the muscle serves to approximate the bony arytenoid rods lying 

 in the laryngeal cavity. Since Gronberg regards these ossified 

 parts as external arytenoids not represented in other Anura, he is 



* Henle (19. p. 26) states that in the male Pi]pa the whole of the ventral 

 ^8urface of the larynx is covered by muscle, an observation which is not borne 

 out by Gronberg's figure (18. Taf. 38. fig. 18). 



