1899.] THE CARPUS OF CTKNOMIS. 433 



the distal as the metacarpal segraeut of the postmiuiinus." ' In 

 his last utterances on the subject ^ neither the pisiform and cal- 

 caneus, nor the so-called prsepollex and preehallux, are considered 

 as true carpal and tarsal bones, but " they have the sauie rank and 

 position as the metacarpal and metatarsal bones." 



What for palaeontologists has been scarcely doubtful from the 

 beginning of the discussion, becoaies still clearer by the recent 

 researches, viz., that the Tetrapoda have always been penta- 

 dactyle^; so that we may use " Pentadactylia " as synonymous 

 with Tetrapoda. The remaius of supernumerary rays must be 

 traced to stages beyond the tetrapodous. Although a linger (toe) 

 is a ray or part of one, the more general term " ray " (Strahl) is not 

 synonymous with huger (toe) ; to use the two terms promiscuously 

 is equivalent to deliberately confusing the discussion. 



Where we meet among Mammals with an especial development 

 of those supernumerary rays, this condition can always be traced 

 to their secondary adaptation to special functions, as was long ago 

 insisted upon by Winge and others'*. 



As to the pisiform, a more or less ossified distal element seems 

 to be a common occurrence among Eodentia; apart from Batliy- 

 ercjus and Ctenomi/s, I find it in all the species of Mas up to the 

 present examined (pd. fig. 4), including Mus decumanus and Mus 

 alexandrinus ; it is present too in Brachyuromys ramirohitra and 

 in Arvicanthis niloticus (fig. 5, pd.). In all of these its special 

 development is apparently due to an adaptation to either climbing 

 or fossorial functions (to the latter in Baihyergus, Ctenomys, Mus 

 nativitatis), or to both combined. 



The so-called os Daubentonii of the Gibbon, about which more 

 will be said farther on, is according to an observation by Leboucq, 

 the most proximal part of the Mammalian pisiform ; from its 

 position it cannot be considered as an " ulnare autebrachii " (Thile- 

 nius) : but seems to be the only part of the pisiform belonging to 

 the carpus. 



1 P. Z. S. 1889, p. 260. 



2 P. Z. S. 1894, p. 373.— ' Hand und Fuss,' p. 312. 



^ Cf. e. g. Emery, in Semon's ' Forschuugsreise,' ii. p. 399 (1897) : " Die Zahl 

 der echten Finger und Zehen ist und war iminer auf f iinf beschrankt." 



* In his " Reterat" (p. 336), von Eardeleben admits that this may be the case 

 with the " prisepolles" of Pedetes, although on a preceding page the same had 

 teen adduced as a conviuchig argument in favour of his case : •' . . . drittens 

 suchte Eef. nach Siiugetieven, die uicht nur das Rudiment eines PrtEpollex, 

 sondern eiuen ' wirklichen Finger ' batten — im Sinne Geyenbaur's, der dafiir 

 ein Metacarpale und einige Phalangen verlangt. 



" Nach clem alteu, so recht fur den VVahlspruch eines Naturforschers geeigneten 

 Worte : ' Suchet, so werdet ihr finden,' gelaug es damals (1889) auch, nicht 

 uur bei Beptilien, fossilen und lebenden Schildkroten u. a. eiuen Pra?pollex und 

 Pi'sehallux nachzuweisen, sondern sogar .S'a«^e//ere zu finden, bei denen derPra- 

 poUex {Pedetes capensis), oder der Postminimus {Bathyergus maritimus) aus 

 sttee'Knochenbesteht . . . .Pedetes besitzt aber nicht nur zwei Knochen im Pra;- 

 poUexskelet, sondern einen wirklichen 'Finger' mit einem breiten, fein- 

 gestreiften Xagel, mit Falz etc., wie Eef. I'lir die drei Londoner Exemplare 

 festgestellt hat " (I. c. p. 283). 



