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Show 170 PROF. G. B. HOWES AND W. RIDEWOOD ON [Mar. 6, Born records (6, p. 55) individual variations in the constitution of the pre-hallux; we agree with him only so far as concerns the presence of three segments irrespective of our tarsal one (cf. p. 14J). The terminal one of these is never recognizable in the adult (fig. 23), and we have failed to find it in Pseudophryne. e. CYSTIGNATHID_E. Examined :- 5 Limnodynastes tasmaniensis; L. dorsalis. Leptodactylus pentadactylus : 140 m m. Leptodactylus albilabris: 23 m m. Ceratophrys ornata : 140 mm. Ceratophrys americana.. Chiroleptes australis. Crinia varia. 3 Pseudis paradoxa, tadpoles. 2 Hylodes martinicensis. Telmatobius jelskii, tadpole. Paludicola bibronii. 4 Heleioporus albopunctatus. Fore Foot (figs. 25, 26, and 28). Gegenbaur (18) and Hofmann (21) have alluded casually to the limb- skeleton of one or two genera of this family ; but the most complete account yet published is that of Mayer (27). The skeleton of the fore foot resembles, in its general aspect, that of the Frog ; and in a family where three of the eight carpal elements are invariably fused together (capitato-hamatum, 3, 4 k) there is little room for modification of any morphological importance. The carpus of Limnodynastes (fig. 28) may be conveniently taken as a type of the whole family. The naviculare (n) lies well towards the radius, being prolonged forwards into a thin edge. The pollex carpal is free and little modified, carrying the pollex (po. ii.). This consists of a single element which is, in the male, shovel-shaped and beset by a horny investment, much in the manner of the calcar in Pelobates or Heleioporus. The following are the more important departures from the above that we have observed in the genera recorded : - Pseudis (fig. 26).-The second digit is remarkable for its slenderness, while it is closely related to the pollex, and, with it, opposable. This change is accompauied by a corresponding increase in calibre of the head of the 3rd metacarpal (3'). The carpal of the pollex is greatly elongated, in excess even of that which is seen in the Hylidce. Ceratophrys.-The naviculare here lies in the proximal row, and offers a broad surface for articulation with the radius. The carpal of the pollex is stouter than that of the second digit, and it bears two short, but well-defined and fully ossified, segments l. Leptodactylus.-The naviculare is here in full articulation with 1 This is also the case in Paludicola. |
