344 



vestibulum is proved by the soft white calcareous concrenient. Such 

 I found to be the structure of ear in Hcmisus yuttatum and Mi- 

 crhyla. In Phrynisciis tceris and nigricans and in Brachycephalus 

 the osteutn 'pharyngeum of the tube is more open. Rhinophrymis 

 donsalis exhibits the following details: — After removing the skin, an 

 aperture of the ear is no more to be observed than a tympanum ex- 

 ternally, tbe whole region being covered with muscles. The most 

 accurate and repeated examination of old and young individuals did 

 not enable me to find any osteutn pharyngeum of the tube ; there, 

 where it might be supposed to be situated, on the sides of the pala- 

 tum molle, I found only a very short and flat groove, perhaps the 

 same seen by Bibron, who describes the Eustachian tubes as ex- 

 cessively small. After removing the muscles, the external entrance 

 in the ear becomes conspicuous ; it is the fenestra ovalis vestibuli, — a 

 large opening with rounded outlines, formed by swollen edges of the 

 os petrosum. This opening is closed by a cartilaginous operculum, 

 internally concave, externally convex, and so inserted by a membrane 

 in the bony ring as to be rendered moveable. Round the bony ring 

 arise some muscular fibres, which continue to the front edge of the 

 shoulder blade. Other muscular fibres, having arisen from the centre 

 of the operculum, join them ; and their function is, by moving the 

 operculum outwards, to enlarge the cavity of the vestibulum. The 

 vestibulum itself is spacious, cpiite bony, and forming an externally 

 conspicuous, thin, flat bulla. In the interior is enclosed in the 

 saccum vestibuli, — a large, rounded, white and soft calcareous concre- 

 nient. Besides the fenestra ovalis are to be observed 3-4 minute 

 openings, through which a bristle can reach immediately the cavity 

 of the skull, and a larger one, oval, near the canales semicirculares. 



Thus we find in these Anura slight modifications in the type of the 

 structure of the ear, as it is found in the Ccecilice and Urodelce (Am- 

 phiuma, Menopoma, Siredon, Protevs, Triton, Salamandra), — a cir- 

 cumstance, which directs us not to neglect it as a character for 

 systematical arrangement; and thus I divide the Opisthoylossa oxy- 

 dacfyla and platydaetyla into the following sections : — 



I. Opisthoylossa oxydactyla. 



\. With maxillary teeth and perfectly-developed ear : lianina. 



2. With maxillary teeth and imperfectly-developed ear : Bont- 



Ijinatorina. 



3. "Without maxillary teeth, and with imperfectly-developed 



ear : Brachycephalina. 

 [. Without maxillary teeth, and with perfectly-developed ear : 

 Bufonina. 



I I . Opisthoylossa platydaetyla. 



1. With maxillary teeth and perfectly-developed ear : llylnin. 

 '2. With maxillary teeth and imperfectly-developed ear: Mi- 

 crhylina. 



