of the Hand in Pipa and Xenopus. 199 



young specimen of 19 niillim. length, and thus its nature 

 as a sesamoid seems to be proved ; moreover, they have 

 shown that the bony piece C] is preformed in cartilage 

 like the true carpalia, and originally without connexion with 

 metacarpale II ; thus its interpretation as a true carpal bone 

 would seem to be accepted by others besides " Dauraen- 

 Entliusiasten " (Briihl). The process x is said to be 

 wanting. 



That Briihl, Howes, and Ridewood, though they rightly 

 distinguish the radial and ulnar sides, yet confound the dorsal 

 and volar sides, seems to be explained by the singular form 

 of the metacarpals (c/i below) ; the confounding of the riglit 

 and left fore limbs is a mere consequence of the first error, 

 and would be easily intelligible if the observers had only had 

 to do with isolated limbs. This seems partly to have been 

 the case with Howes and Ridewood, as they (/. c. p. 143) 

 mention having received limbs of Pipa from Prof. Wieders- 

 heim ; but besides they have examined a large male and a 

 complete young specimen, and this being the case I am not 

 able to account for their mistake. 



As to the question how the carpals of Fipa are to be 

 understood and named, we first meet with the difficulty that 

 the interpretation of the anuran carpus is not at all univers- 

 ally settled, and secondly that Pipa in several points is some- 

 what exceptional. 



Generally the proximal series of the anuran carpus consists 

 of two bones, which Gegenbaur * regards as radiale and 

 ulnare ; in the distal series there may be one piece to each 

 metacarpal, called by Gegenbaur carpalia 1-5, as in XenopuSj 

 where all the bones are well developed (c/. figs. 5, 6, p. 205) ; 

 but most frequently the number of these pieces is reduced 

 through coalescence (e. g. in Hyla^ Rana, Bufo, &c., the 

 metacarpalia III-V being here carried by one carpale) ; and 

 finally on the radial side there is generally interposed a larger 

 piece, interpreted by Gegenbaur as a dislocated centrale ; in 

 some cases it extends upwards beside the radiale and joins 

 the radius, so that it seems to belong to the upper series, 

 which consequently would acquire the three pieces typical to 

 most vertebrates ; this junction with the radius, however, is 

 of secondary nature and is wanting in younger stages, so that 

 the proximal series really contains but two bones. Concerning 

 the ulnar bone, all authors agree as to its corresponding to the 

 ulnare ; its constant position outside a branch of arteria 



* Unters. zur vergl. Auat. cits Wiibelthicre : " Carpus uucl Tarsus," 

 1864. 



