OCR Text |
Show 1897.] HYOBRANCHIAL SKELETON OF PELODYTES PUNCTATUS. 577 EXPLANATION OF PLATE XXXIV. Fig. 1. Euryope bipartita, p. 549. 2. nigricollis, p. 550. 3. Lefevrea ceneicolle, p. 527. 4. Ehembastus maculicollis, p. 538. 5. Diboloides bicolor, p. 553. 6. Neodera transversicollis, p. 564. 7. Serraphula cenea, p. 557. 8. Eugonotes longicornis, p. 559. 9,10. Candezea variopennis, p. 574. 11. Luperus nigrosuturalis, p. 567. 12. Aulamorphus hollisi, p. 572. 4. On the Structure and Development of the Hyobranchial Skeleton of the Parsley-Frog {Pelodytes punctatus). By W. G. BIDEWOOD, D.Sc, F.L.S., Lecturer on Biology at St. Mary's Hospital Medical School, London. [Eeceived M a y 3, 1897.] (Plate XXXV.) When writing recently upon the Hyobranchial Skeleton of Xenopus aud Plpa I adverted to the fact (16. p. 116) that the hyoglossal foramen so characteristic of these two genera is most nearly paralleled among the phaneroglossal Anura in Pelodytes, and (16. p. 117) that in the hyoidean cornu of Pelodytes is seen the retention of a condition of dissolution which is transient in Plpa. The opportunity for a more exhaustive study of the hyobranchial skeleton of Pelodytes has since been afforded to m e by Mr. Cr. A. Boulenger, F.E.S., of the Natural History Museum, London, who most generously placed at m y disposal an extensive series of larvae collected by himself, and in an excellent state of preservation, together with numerous adults of the same species (P. punctatus) both living and in spirit. The hyobranchial skeleton of the adult Pelodytes is remarkable in many ways, and, except in the case of the thyrohyals and the postero-lateral processes adjoining, it is difficult at first sight to see what relation exists between the various parts and those of the more familiar hyobranchial skeleton of the C o m m o n Frog. The anterior or hyoidean cornu is divided; and the detached posterior portion, flat and broad in front (li, fig. 9, Plate X X X V . ) , tapers backwards into a curved rod of cartilage (h"), which rises up to be attached to the auditory region of the skull. The study of the metamorphosis of the hyoid arch (postea) shows that in the adult but little is missing of its total length. The only part of the arch which is not represented in the adult skeleton is that between the anterior extremity of the cartilage marked h' in fig. 9 and the part of the great plate marked h. The relations are readily grasped by referring to the hyoid of the recently metamorphosed animal (fig. 8), where the lateral foramen (fi, fig. 9) has not yet been |