436 ON THE CARPUS Of CTENOMYS. [Apr. li^, 



centralo-trapezoid, viz., the result of a fusion of these two ossicles, 

 which remain distinct in Bathyergus and Gtorychus ; and that hke- 

 wise in the tarsus of Myoscalops the single bone is a scapho-meso- 

 cuneiforme. However, on examining closely the tarsus of 

 Myoscahps, I discover an almost imperceptible ossicle, comparable 

 to a minute pin's head, attached to the proximo-tibial angle of the 

 second metatarsal ; this cannot well be anything else than the greatly 

 reduced mesocuneiform, whose place and function has devolved on 

 the enlarged navicular. We may further conclude, per analogiam, 

 that the single bone in the carpus of Myoscahps is not a compound 

 of the centrale with the trapezoid, but that the former has usurped 

 the place of the latter, which has either completely vanished, or 

 had become so minute that it was removed in the cleaning of the 

 carpus. 



The same reasoning cannot however be resorted to in the case 

 of the supposed lunar of the above-mentioned Muridae, because in 

 LepidoIcmu7' I have come upon an ossicle (cv, fig. 6), occupying 

 exactly the same position on the palmar side as iu the Rodents ; 

 whereas in Lepidolemur an undoubted lunatum is present besides. 

 We must therefore look elsewhere for the homologue of the 

 accessory ossicle of Muridae, Lejndolemur, and possibly also of the 

 above-named Mai'supials. 



Kohlbriigge describes and figures in the carpus of Hylohates 

 syndactylus a small bone, situated between the radius and the 

 ulnare ; " a fibrous ligament connected the ossicle with the radius 

 and the ossiculum Daubentonii, cartilaginous tissue intervening 

 between both."^ Kohlbriigge calls the ossicle ^' ossicidum Cam- 

 perii" the here following description by Camper of a similar 

 occurrence in the " Mandrill " referring apparently to the same 

 ossicle : " In the man us of the Mandrill I found on Feb. 9th, 1779, 

 a fourth supernumerary ossicle in a ligament, which took its 

 origin from the outside of the triquetrum and was inserted on the 

 navicular, which latter was fastened to the radius by a small liga- 

 ment,"^ Thilenius identifies this ossiculum Camperii with the 

 " intermedium antebrachii " of the human embryo ^, which in one 

 instance was found in adult man by Pfitzner'^. The last-named 

 author found besides an "intermedium antebrachii" in the left 

 fore-limb of a Pliascolomys ^ ; the specimen is figured by Thilenius^ : 

 it presents itself in the form of " a roundish ossicle, situated 



1 J. H. F. Kohlbriigge : " Versuch einer Anatomie des Genus Hylobates." 

 M. Weber, Zool. Ergebn. einer Reise in Niederlandisch Ost-Indien, i. pp. 338, 

 339, pi. xvii. fig. 10 (1890-91). 



^ ' Naturkundige Verhandelingen van Petrus Camper over den Oraug Outang 

 etc.,' p. 87, footnote (b) (1782). 



^ G. Thilenius : " Das Os intermedium antebrachii des Menschen," Morph. Arb. 

 V. p. 8(189.5); id., " Unters. lib. d. morpbol. Bedeut. accessor. Elemente am 

 men.schl. Carpus (und Tarsus)," Morph. Arb. v. p. 501 (1896). 



■* W. Pfltzner, in Verb. Anat. Ges. 7. Vers. Gottingen, p. 191 (1893) 

 ("Triquetrum seoundarium") ; id., Morph. Arb. iv. p. 505 (1896). 



' Verb. Anat. Ges. 7. Vers. Gottingen, I. c. 



" Morph. Arb. v. pi. i. fig. 12 (1895). 



