SKELETO]S" AliTD LA.RTNX OP XEISTOPUS ATfD PIPA. 61 



ginous side-wall of the larynx, which, is of considerable value as 

 a guide to the recognition of homologous parts in Xenopus and 

 Bana (see p. 62), The floor or ventral wall of the larynx lias 

 the form of an extensive plate of cartilage, incomplete only in a 

 pair of elongated membranous areas (PL 8. fig. 1,/') towards its 

 anterior end, where the anterior fiftbof the thyrohyal remains free. 

 The floor of the larynx is produced posteriorly into a pair of 

 cartilaginous bands {hr.) with very irregular edges, which run 

 back along the mesial surface of the bronchi, in the possession 

 of which latter the Aglossa depart again from the anuran type. 

 The irregular outgrowths from the sides of the bands extend 

 only to the middle of the upper and under surfaces of each 

 bronchus, so that the outer half of the bronchial tube is entirely 

 membranous. These bronchial prolongations of the cricoid 

 cartilage are not unrepresented in other Anura, for in the 

 Discoglossidse (e. g. Discoglossus) two thin cartilaginous bars 

 run back from the floor of the larynx to the under surface of 

 the root of the lung, where they end in a cross-piece, T-shaped, 

 which may be regarded as equivalent to one of the bronchial 

 half-rings of Xenopus. In Alytes these rods are even more 

 elongated than in Discoglossus, but the terminal T-piece is very 

 little developed. In Bomhinator the processes are quite short 

 and stout (PL 11. fig. 13, h\). Even in Bana the opening of the 

 lung into the larynx is supported by a ring of cartilage which 

 sends ofi" irregular processes on to the lung. The strongest of 

 these (PL 9. fig. 7, hr.), running along the ventro-internal aspect 

 of the lung, would appear to correspond with the process already 

 referred to in the Discoglossidse, and with the bronchial cartila- 

 ginous band of Xenopus. The roof of the larynx of the female 

 Xenopus is deeply notched behind (PL 8. fig. 3), so that a mem- 

 branous area intervenes between the cricoid and bronchial 

 cartilages. The anterior edge of the roofing cartilage is 

 delicately rounded, and is rather thicker than the other parts. 

 The antero-posterior diameter of the roof is not more than twice 

 the transverse diameter. 



The arytenoid, like the cricoid, is exceptionally shaped. The 

 sides of the glottis are supported by a pair of delicate cartila- 

 ginous flaps (PL 8. fig. 3, ar.) which, from their relations to the 

 glottis and to the laryngeal muscles, evidently correspond to the 

 arytenoid cartilages as we find them in the common frog. They 

 are continued backwards into relatively massive processes {ar.') 



