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Show 1888.] THE CARPUS AND TARSUS OF THE ANURA. 169 The pre-hallux is present in all specimens examined by us ', and it consists in them of four segments-a proximal larger one or tarsal (ph. i.), a smaller metatarsal, and two dimiuutive phalanges2. The retral process of the second or metatarsal segment (* of fig. 19) is absent in Phyllomedusa (fig. 19 «). In an old specimen of Hyla lichenata, on the other hand, it was completely segmented off on either side, forming (woodcut, fig. A, p. 151) the largest of a series of nodules which fringed the free border of the pre-hallux fold. W e have already discussed tbe probable significance of these. d. BUFONID-E. Examined :- Bufo vulgaris. Bufo viridis : large specimen. Bufo calamita : 8 young. Bufo variegatus: young. 8 Pseudophryne bibronii. Fore Foot (fig. 22). The limb-skeleton of Bufo has been described by various authors ; it was first figured by Brandt and Ratzeburg (8), and subsequently by Mayer (27). Gegenbaur, Owen, Born, and Wiedersheim have in turn dealt with this skeleton, and upon some of their observations we have already commented. Pseudophryne (fig. 22) is exceptional among the members of this family in the characters of its carpus : in Bufo the naviculare (n) articulates directly with the radius, and lies in the proximal row, here it is comparatively small and central: in Bufo the 3rd and 4th carpalia and our postaxial centrale coalesce to form a capitato-hamatum, as in the Common Frog. In Pseudophryne there are three carpals lying to the inner side of the large capitatum (4 k), whence it follows that cp. 3 is distinct as in Pelodytes. The carpus of Pseudophryne approximates more nearly towards that of Pelodytes than any other genus yet examined; and considering that the Bufonidce are, with respect to the confluence of their distal and postaxial central elements, a stage in advance of the Pelobatidce, Pseudophryne is to them what Pelobates is to the latter. Hind Foot (fig. 23). W e can confirm Born's statements concerning the tarsalia in this family (3, p. 443) regarding the homology of the element marked (2, 3) with the tarsalia of the second and third digits, and we find that in old specimens this may become shortened-up in a manner suggestive of the Tree-Frogs. W e have nothing to add to what we have already stated in confirmation of Gegenbaur's observations concerning the ligamentous 4th tarsal (cf. p. 145). 1 Leydig states that he was unable to find its cartilages in H. arborea (25, p. 181). 2 Born has described and figured the details of ossification of these, subsequent to fusion, in a very old specimen of H. arborea (6, pi. 1. figs. 1 and 2). |
