508 DE. C. I. FOKSYTH MAJOE ON 



corresj)onding part no facet, but instead, either a convex swelling of the region, or in some 

 cases, on the contrary, a more or less rugose depression. In Lagomys {L. riifesceiis and 

 L. melanostomus) there is the facet in the same place, and articulating with it a 

 comparatively large orbicular or triangular ossicle. I think it probable that, in those 

 Leporidfe {Caprolagus hispidus, C. Netscheri, Sylvilagus brasiliensis) where the corre- 

 sponding region of the Metat. V is raised to a convex protuberance, the ossicle in question 

 has become fused wdth the former bone. 



A similar ossicle has been met with by Pfitzner iu Carnivora, viz. in Ursiis ai'ctos and ' 

 in Lidra *. I find the same ossicle in Cercojiithecidye, in Mus, and, among Insecti- 

 vora, in Erinaceus, Gymnura, Myogale, Condylura and Ceutetidse {Limnogale, 

 Oryzoryctes, Ilicrogale). In the latter, and in Myoyale, it is enlarged transversely and 

 extends also on to the base of Metat. IV. 



Pfitzner homologizes the ossicle in Carnivora with a similar one on the fifth metacarpal 

 of Primates (os hamuli), and regards these and similar occurrences in the third tarsal 

 ray (os unci, in Feliti) as carpalia (or tarsalia) which have become " abortive," and have 

 been secondarily displaced towards the volar side f . The question would then arise 

 whether we have to consider the ossicle of the Metat. V as pertaining to the fifth or to 

 the fourth ray ; for from its position — and the same remark applies to the " os hamuli " — 

 on the tibial side of the Metat. V, and sometimes articulating with Metat. IV also, it may 

 belong to either. For the present the question cannot be settled ; but since both tarsal 

 and carpal elements in question are of apparently widespread occurrence, we may hope 

 to get better acquainted with tliem before long. In the marsupial Permneles ohesula, 

 Metat. IV and Metat. V have each a separate plantar bone, articulating Avith their 

 proximal capitulum %. 



On the dorsal side of the tuberosity of Metat. V — on the left in fig. 9« — is seen what 

 appears to be a facet, partially extending to the volar side also. The same facet is 

 present in both species of Frulagus. It at once recalls to mind what occurs on the 

 Metac. V of P/-oJagui> and Lagomyti, and some Leporidaj, where carpale 5 (os vesalianum 

 carpi) articulates with the tuberosity. 



A distinct os vesalianum tarsi (Pfitzner) is a very rare occurrence in Man, in whom it 

 has been seen by Vesalius, Gruber, and Spronck §. Pfitzner never saw it free; when 

 distinct — one case figured by Vesalius, two described and figured by Gruber, one by 

 Spronck — it is situated on the fibular side of the pes, " in the angle between the cuboid 

 and Metat. V, articulating Avith both." An epiphysis which may occur on the tuberosity 



* Tageblatt der 60. Vers, deutsch. Naturf. und Aerzte in Wiesbaden, p. 251 (1887). — Speaking of the Bear, the 

 author states that the ossicle occurs on the plantar base of Metacarpal V ; from the context it would appear that 

 this is a misprint for Metatarsal V • at anj' rate, in Lutra it is present on both Metacarpal and Metatarsal V, as 

 stated by the same author. 



t Morph. Arb. i. pp. 7, 8 (1S9I) ; 541, 542, 587 (1892) : iv. p. 539-543 (1895). 



+ C. Emery, " Beitr. z. Entwicklungsgesch. u. Morph. d. Hand- u. Fussskeletts der Marsupialia" (Semon's 

 ' Forschungsreisen in Australieu,' &c., ii. p. 381, Taf. sxxv. figs. 45, 46 (1897). 



§ Morph. Alb. i. pp. 522, 595, 596, 756, 757 (1892) ; vi. pp. 472-475 (1896). 



