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Show 436 ON THE CARPUS OF CTENOMYS. [-^Pr- 1^> centralo-trapezoid, viz., the result of a fusion of these two ossicles, which remain distinct in Bathyergus and Georychus; and that likewise in the tarsus of Myoscalops the single bone is a scapho-meso-cuneiforme. However, on examining closely the tarsus of Myoscalops, 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. W e may further conclude, per analogiam, that the single bone in the carpus of Myoscalops 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 Lepidolemur I have come upon an ossicle (x, tig. 6), occupying exactly the same position on the palmar side as in the Rodents; whereas in Lepidolemur an undoubted lunatum is present besides. W e must therefore look elsewhere for the homologue of the accessory ossicle of Muridae, Lepidolemur, and possibly also of the above-named Marsupials. Kohlbriigge describes and figures in the carpus of Hylobates 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."1 Kohlbriigge calls the ossicle '•ossiculum Cam-perii," the here following description by Camper of a similar occurrence in tbe " Mandrill " referring apparently to the same ossicle : " In the manus of tbe 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 ligament." 2 Thilenius identifies this ossiculum Camperii with the " intermedium antebrachii" of the human embryo 3, which in one instance was found in adult man by Pfitzner1. Tbe last-named author found besides an "intermedium antebrachii" in the left fore-limb of a Phascolomys 5; the specimen is figured by Thilenius1': it presents itself in the form of " a roundish ossicle, situated 1 J. H. F. Kohlbriigge: " Versuch einer Anatomie des Genus Hi/lobates." M. Weber, Zool. Ergebn. einer Reise in Niederlandisch Ost-Indien, i. pp. 338, 339, pl. xvii. fig 10 (1890-91). 2 ' Naturkundige Verhanrtelingen van Petrus Camper over den Orang Outang etc.,' p. 87, footnote (b) (1782). 3 G. Thilenius: " Das Os intermedium antebrachii des Menschen," Morph. Arb. v. p. 8(1895); id., " Unters. lib. d. morphol. Bedeut. accessor. Elemente am menschl. Carpus (und Tarsus)," Morph. Arb. v. p. 501 (1896). 4 W . Pfitzner, in Verh. Anat. Ges. 7. Vers. Gottingen, p. 191 (1893) ("Triquetrum secundarium"); id., Morph. Arb. iv. p. 505 (1895). 5 Verh. Anat. Ges. 7. Vers. Gottingen, I. c. 6 Morph. Arb. v. pl. i. fig. 12 (1895). |