FOSSIL AND RECENT LAGOMORPHA. 497 



pisiform I find in tlie liys-tiicine Cfenomys and in Mus, and it will probalily be met with 

 in many otlier fossorial and climbing Rodents. 



What seems to be a remarkable adaptation of the distal pisiform to a special function 

 is exhibited l)y the strong cartilage, whicli in Fteromys is prolonged to support the 

 lateral membrane serving as a parachute. Thilenius makes of it an element of an 

 antebrachial series, his " ulnare antebrachii " * ; but he is misled by Owen's much reduced 

 figure of the skeleton of a " Fteromijs voluceUa "f, in which the detached cartilage has 

 been drawn proximally to the pisiform and separated from it by a small interspace. 

 The true connection of this cartilage was already known to Buffon %■ He described it as 

 a bone ; but in the only skeleton {Pteroyuiis m<(gnificiis) at the Natural History Museum 

 in which this element is preserved it is perfectly cartilaginous, and as such it is described 

 by Owen in Sciuropterm coliicella §. In Pteromi/s magnificus it is chiefly attached to the 

 distal end of the pisiform, and, by a much smaller process, to the tuberosity of the fifth 

 metacarpal. Its direction is in the beginning right backward, in the prolongation of the 

 long axis of the osseous pisiform ; but gradually it turns upward, forming in its entirety 

 a semicircle. It might be maintained that the patagial cartilage of Sciuropterini is in 

 origin quite extraneous to the pisiform, and that it has only secondarily become supported 

 by this widely projecting bone. With the scanty material at my disposal, I am not in a 

 position to follow up the matter closer, nor is this the place to do so. A clue might be 

 obtained from young specimens of ttercmtjs; and if they should show both the usual 

 pisiform epiphysis and the patagial cartilage, they would support the view of an extraneous 

 origin of the latter. 



The lengthened subcylindrical bone which in the insectivore Cht'ijsochloris extends 

 from the carpus to the humerus, " simulating a third antebrachial bone," was considered. 

 by Meckel ||, followed by Cams ^, Peters **, Giebel ff , and Dobson %% as an ossification of 

 a tendon ; regarded by the latter three as that of the m. flexor digitorum profundus. 

 Cuvier §§, ^l. Wagner || H, Gervais^^, and Owen*** homologize this bone with the pisiform. 



* Morph. Arb. (Schwalbe) v. p. 508 (1895). 

 t 'Anatomy of Yertebnites," ii. p. 385, fig. 154 (18611). 



i; "II y a de plus dans le polatonche im os (AA) lon,a de 5 lignes, en forme d'aivte ou d'eperoii. qui tieut au 

 (|uatrieme os du premier rang du carpe, of qui s"etend oljlicjuenienf en arriere et en liaut le long du bord de la 

 membrane qui forme les ailes de eef animal." (Hist. Na( . gon. et partic. x. p. 11:3, pi. xxiv. 17():>.) 

 § L. e. 



II System d. vergl. Anat. ii. (2) p. 374 (18:25). He ealls tbe element " ein voni Streekknorren des Oberarmbeins 

 zum Speiebenendo [it is, bowever, on the ulnar side] der Ilandwnr/.el gehendes, starkys, verknijcbertes Band.'" 



^ " . . . ein drifter Knochen des Untergliedes, welcher jedocli nur als eiue yerkniiehcrte Sehne, oder vielmehr ganz 

 verknocherfcr Muskel (fle.vor carpi, nhiaris), anzusehcu is'."' — C. G. Carus, Krlauteriingsfafeln zur vergleichenden 

 Anatomie, ii. p. :')1, Taf. it, fig. Ill, //' (18l'7). 



** W. Peters, iS"atur\v. Eeise uacb Jlossambique, Zoologie, i. p. 72 (1S52). 

 +t Giebel, in Ijronn's Klassen u. Ordnungcn, vi., v. p. 534 (1879). 

 jj G. E. Dobson, 'A Monograph of the Inseetivora," ]). 121 (1882). 

 §§ G. Cuvier, Lecjons d'Anat. Comp. 2'' ed. i. p. 42i; ( 1S35). 

 illi Schreber's ' Saugthiere,' Suppl. ii. p. 12(1 (1841). 

 ^T P. Gervais, Hist. Nat. des Maramileres, i. ]). 252 (1854). 

 *»* P. Owen, ' On the Anatomy of Vertebrates," i. p. 392 (18GG). 

 SECOND SERIES. — ZOOLOGY, VOL. VIL 69 



