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Show 174 PROF. G. B. HOWES AND W. RIDEWOOD ON [Mar. 6, family, and with the exception of a broadening of the pollex in Cornufer and Rhacophorus, and an increase in size of the proximal end of the pre-hallux metatarsal segment in the first-named genus, we have met with no important departure from what is seen in the Common Frog. As this animal is so largely in demand for ordinary class use1, we append a somewhat detailed description of its hrnb-skeleton, in the light of our preceding observations. Fig. B. Eana temporaria, 2 , 54 m m . in length. Left fore foot, dorsal view, x 12. The coalesced radius and ulna (r. u) are represented in tbe natural position. For references see p. 182. Fore Foot (Rana temporaria). In the adult carpus of this animal, six bones may be recognized, all of which are in their original positions with the exception of the naviculare (n). This has, as already remarked (p. 158), undergone elongation and displacement radially. W e were not a little surprised to find that there is considerable variation in the position of this element in young Frogs, whose carpus and tarsus were still unossified. In a large series of specimens examined, measuring at 1 The descriptions given in the students' manuals (Huxley & Martin's ' Elein. Biology,' Marshall's ' Frog,' and Mivart's ' C o m m o n Frog ') are for the most part compilations, and we deem it unnecessary to criticise them in detail. |