SKELETON AKD LAETNX OF XENOPTJS AKD PIPA. 63 



very far bact (see PL 8. fig. 3), and the union is brouglit about 

 in Xenopus by tbe confluence of tbe cartilages and not by- 

 ligament as in tbe frog. Henle states (p. 14) that in Alytes 

 dbstetricans, Bufo cinereus, Itana esculenta, and Rmia temporaria 

 the larynx is connected with the epiphysis of the thyrohyal by 

 continuous cartilage. I have examined these four species, and 

 have found the connexion to be ligamentous in all. Wilder 

 refers (42. p. 286) to a cartilaginous union in Sufo lentiginosus, 

 but the difficulty of obtaining this species in England has pre- 

 vented me from checking the observation. Eelatively to the size 

 of the vrhole body, the arytenoids are much smaller in Xenopus 

 than in the frog, although the larynx as a vs^hole is very much 

 larger. I have elected to institute this comparison with the 

 larynx of the edible frog, not merely because the figures of the 

 latter by Ecker (12) and others are so familiar to the majority 

 of anatomists, but also because of the fact that the laryngeal 

 skeleton of the female Xenopus will bear a closer comparison 

 with that of JRana esculenta than with that of any other species 

 of JRana. It is true that Wilder (42. p. 287) has shown that 

 the larynx oiHana esculenta is not typical of Anura, nor even of 

 the genus ^ana ; but by the very possession of the posterior 

 ventral bar of the cricoid (PI. 9. fig. 7, c"), in which it departs 

 from the other species of the genus, the larynx of the edible frog 

 approaches the nearer to that of Xenopus. 



In spite of this parallelism existing between the larynx of 

 Xenopus and that of the frog, an extensive study of the skeleton 

 of many different genera of Anura has convinced me that 

 that amphibian (Pipa excepted) the hyobranchial and laryngeal 

 skeleton of which most nearly approximates to that of Xenopus 

 is undoubtedly JBombinator — a determination which I had arrived 

 at prior to the publication of the hint to the same efiect by 

 Wilder (42. p. 291). The notch at the front of the hyobranchial 

 basal plate in this toad is excessive, so great in fact as to leave 

 only a narrow transverse isthmus connecting the right and left 

 halves, as in some Hylidaa *. The paired ossifications in the 



* In spite of the depth of the notch at the front of the basal plate, the point 

 at which the hyoglossal muscles rise above its level is not in any way thrown 

 back. The notch is closed by a membrane, the front edge of which lies nearly 

 straight and is situated a considerable distance in front of the incised cartilage. 

 This holds good also for Alytes, Biscoglossus, Eana, Bufo, and most Anura 

 where the notch is at all deep. In Xenopus the hyoglossal muscles rise 

 immediately in front of the cartilage that forms the posterior border of the 

 oval foramen, while the membrane spreads out in front over the rest of the hole. 



