| OCR Text |
Show 500 PROF. G. B. HOWES ON AN UNRECOGNIZED FEATURE [Julie 7, d. Epiglottis and epilaryngeal folds both absent. Bufo typhonius. 2 • Cornufer vitianus. 2 • *Hyla meridionalis. 3,2- venulosa. 3 • *Hylodes martinicensis. 2 ju v - Nannophrys ceylonensis. 3 • Phryniscus Icevis. 2 • Phyllomedusa bicolor. 3 juv. * Rana esculenta. 3, 2- * temporaria. 3,2- temporalis. 3 • Rappia marmorata. 2 • Rhacophorus maculatus. 3 >2 • Rhinoderma darwini. 3 • Xenophrys monticola. 2 • Perusal of the above brings into prominence a wide range of individual and specific variations. The former are, however, less striking than appears at first sight, and little more remarkable than those of the Amphibian manus and pes, or of the Batoid intestinal valve1; the latter find a near parallel in the modifications of the larynx in certain fruit-eating Bats recorded by Dobson2. That observer has obtained a satisfactory explanation of the phenomena upon purely physiological grounds, and the analogy suggests that an investigation into the habits of the living Anura under consideration might furnish a similar clue. If, as the analogy to Chiroleptes would suggest, the folds in question are associated with the development of vocal sacs, it is difficult to reconcile their absence in Hyla meridionalis and H. venulosa, with their presence in H. dolichopsis and Bombinator; while the combination met with in Heleioporus would appear to negative the supposition. It may be held that the structures are developed periodically or with sexual maturation; but, if so, it becomes hard to account for their insignificance iu the male of Leptodactylus (fig. 2), in which the accessory spurs had attained a considerable development. The facts adduced in Chiroleptes australis, while they appear to favour this belief, are, in themselves, capable of a different interpretation, for that the differences between the two males which I have examined are due to age is a surmise. The facts are very puzzling; but who is to say that, in the most marked cases recorded, we may not be dealing with a character of taxonomic value, fit at least to rank with those customarily relied upons. Apart from the above considerations, examination of tbe figures shows most conclusively that, in the specimens which I have described, a gradational modification can be traced. Chiroleptes (fig. 6) and Rana (fig. 1 b) stand at opposite ends of a series, the intermediate steps in which are furnished by Ceratophrys, Leptodactylus, and liana pipiens, in succession. The question therefore arises as to which of the two first-named typifies the more primitive arrangement. 1 T. J. Parker, T. Z. S. 1880, pp. 49-61. 3 P. Z. S. 1881, pp. 685-93. 8 Cf. remarks by Huxley on the "Taxonomy of the Canida." (P. Z. S. 1880, p. 286), and by Herdman, "On the Specific and Local Variations in the Tunicata (First Report of the Liverpool Marine Biological Committee, 1886, pp. 355, 356). |
