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Show 164 PROF. G. B. HOWES AND w. R I D E W O O D O N [Mar. 6, planate with these and not displaced ventrally, it follows that the hind foot is here, like its fellow in front, much more normal than that of Pipa. The calcar consists of three slender elements, the proximal one of which can only represent a tarsal. B. PHANEROGLOSSA. a. DISCOGLOSSIDAE. Examined :- Discoglossus pictus: adult cJ, a young specimen, and a tadpole. Alytes obstetricans : j , gerieg f adultg aQ(j fcad leg Bombinator igneus Fore Foot (figs. 5, 6, 7, 9). Born's latest communication upon the fore foot in Alytes (6) would be little short of revolutionary could his deductions be substantiated. W e have already fully discussed these (p. 157), giving our reasons for rejecting them in toto. The general plan of the carpus in these three genera is very similar ; in all, the largest element of the series is our postaxial centrale (k), and it is in this that ossification first commences. Gegenbaur has already called attention to the fact that in Bombinator it is " nicht gar schwer " to see in the naviculare (n) the centrale of the Urodela; we have already given our reasons for regarding tbis element as a preaxial centrale (p. 159). Gegenbaur says that in Bombinator (18, p. 17) all the carpal elements are distinct; we, however, interpret the 5th carpale of all our predecessors as a postaxial centrale (p. 157). Concerning the remaining carpalia we are at variance with Born ; he figures an individual Alytes larva in which carpale 4 appears to have fused, while still cartilaginous, with cp. 5 (our postaxial centrale)-this we have never observed. He also states that in Bombinator a similar confluence may occur between carpalia 2 and 3 while still cartilaginous; and he remarks that these variations " auf eine Neigung zum (Jeber-gang in die fiir Rana, Bufo u. s. f. characteristische Carpiisform schliessen lassen." W e have searched most carefully for traces of any such fusion, with negative results; carpalia 1, 2, 3, and 4 being throughout distinct in all our specimens. These elements remain for a long time unossified in Alytes (fig. 9), they ossify in order 1, 4, 3, 2 ; in the interval, however, between the ossification of our postaxial centrale and these carpalia, tbe naviculare, ulnare, and lunatum ossify in the order named. The following is the formula for the whole series:- k. n.p. I. 1, 4, 3, 2. The carpal of the 5th digit is represented in all three genera by the ligamentous band previously described (p. 154) ; in Alytes this carries a tolerably large cartilaginous nodule, which we regard as the vestige of the 5th carpale of the Urodela. |