SKELETON AlfD LABTNX OF XEISTOPUS ASIt PIPA. 71 



qualified in respect of tlie female Pipa. The median section also 

 demonstrates the small extent of cartilage in the median line of 

 the roof (fig. 3, c) and floor (c") of the larynx. Owing to the 

 close approximation of the anterior ends of the thyrohyals and 

 the presence of the membranous space in the floor of the larynx 

 there is less difficulty than in Xenopus in recognizing the mor- 

 phological posterior edge of the basal plate of the hyobranchial 

 skeleton (figs. 1 and 3, cc). The fenestra seen in the side-wall 

 of the larynx of Xenopus does not occur in Pipa. 



The bronchi are elongated and are supported by bronchial car- 

 tilages. These cartilages have the form of independent bronchial 

 rings, and are not, as they are in Xenopus, united into a band 

 running lengthwise along the bronchus. The bronchial skeleton 

 is also more complete in Pipa, the rings extending three quarters 

 of the way round, while in Xenopus the lateral projections of the 

 longitudinal bronchial cartilage do not extend more than halfway 

 round. And, what is still more important, the bronchial rings 

 of Pipa are incomplete on the mesial side, whereas in Xenopus it 

 is the external wall of the bronchus that is not supported by 

 cartilage. 



Male. 

 The larynx of the male Pipa is unique and unparalleled not 

 only among the Anura but in the whole animal kingdom. It is 

 almost entirely ossified, and thus contrasts forcibly with the 

 larynx of the male Xenopus which, although more massive and 

 inflated than that of the female, is certainly not more bony. The 

 larynx of the male Pipa is about twice as long as that of the 

 female — five or six times so according to Mayer (25. p. 540), but 

 this computation is excessive. It is proportionately broader in 

 front, so that in a dorsal or ventral view it has roughly the form 

 of a rectangular cushion or pillow. The floor is continued 

 forwards into a pointed process of unossified cartilage, which is 

 attached by ligament (PL 9. fig. 5, i') to the middle of the 

 transverse bar forming the posterior boundary of the hyoglossal 

 foramen. The cartilaginous process at the front of the larynx 

 and the bar bounding the back of the foramen are the posterior 

 and anterior portions respectively of the basal plate of the hyo- 

 branchial skeleton. The ligament connecting them has the same 

 morphological value as the ' cartilaginous isthmus of the female 

 (PI. 9. fig\ 1, i). It must not be confounded with the paired 



