FOSSIL AND RECENT LAGOMORPHA, 509 



of the human fifth metatarsal is considered by Pfitzner * as one of the terminal stages 

 of its assimilation by the latter bone. 



I lind an epiphysis on the tuberosity of Metat. V in the Eodent genera Genrychus and 

 Ctenomys. The bone itself 1 have never seen independent, but, from what I have stated 

 above as to the fossil metatarsal, there can hardly be a doubt that an ossicle articulates with 

 the tuberosity. The cuboid of 'Prolagus, of which I have a number of specimens, shows 

 a facet — absent in Leporidte — on the proximal fibular side ; and this, together with the 

 facet on the tuberosity of Metat. V, suggests the presence in these LagomyidjB of either 

 one ossicle articulating distad with the Metat. V and proximad with the cuboid, or two 

 ossicles, the proximal of the two articulating with the cuboid, the distal with Metat. 

 V ; both possibly articulating originally also with each otlier at their apposed surfaces. 

 Considering the ratlier considerable distance which must have occurred between the two 

 facets, the latter hypothesis — of two bones — seems the more probable. 



The presupposed proximal ossicle would be the homologue of the " os peroneum " 

 (Pfitzuer) of Man f aud other Prioiates, which is the so-called sesamoid in the terminal 

 tendon of the peroneus lougiis muscle. It has in Man, aeeording to Plitzuer, a frequence 

 of about S-9 ° '^, ai)(l is situated on the postero-lateral end of the eminentia obliqua <iviboidei. 

 " Hier findet sich in den Ptillen bester Ausbildung eine scliarf abgesetzte Facette, dereine 

 gleiche auf dem Peroueum entspricht " %. This os peroneum was seen by Daubenton in 

 Hylobates : " II y a de plus dans le gibl)on uu liuitieme os place au cote externe du tarse, 

 a I'endroit ou le ealcaueum touche au cul)oide " §. In the skeleton of a Rylobates lar in 

 the Natural History Museum, there is to be seen an ossicle articulating with the cuboid; 

 and it is of quite general occurrence among the Cercopithecidoe. Gillette mentions it in 

 Monkeys generally as articulating with the cuboid || . Whether the ossicle mentioned 

 by G. Pischer in the Tursius is a vesalianura or a peroneum I cannot decide for the 

 present. He says : "Auch findet man in den Taiseni noch ein iiberziihliges Beinchen, 

 rund, linseuformig, doch liiuglich, Avelches eigentlich auf dem letzten Mittelfussknochen 

 aufsitzt, der sich immer mit seinem Kopfe weit nach hinten zieht "^. I see the " pero- 

 neum " in a minute ossicle in Limnogale (an aquatic member of the Malagasy Centetidfe), 

 adhering to the tendon of the muse, peroneus longus, laterally from the cuboid, and I 

 believe the reason that it has not been more frequently seen in Mammals is that the 

 muscle is generally cut away in preparing tlie skeleton. 



* Morph. Arb. vi. pp. 262, 203, 474 (1^90). 



t Ihld. i. pp. 530, 531, 504-5U8, figs. 12, 13 (1S92) ; vi. pp. 456-462 (1896). 



:|: Iliid. vi. p. 456. 



§ BufFon-Dauljeiiton, Hist. nat. geu. et partic. xiv. p. 106 (1766). 



II " Chez les singes, I'os sesamoide du peronier lateral est tres-volumineux. puisque, ehez des individus de petite 

 taille, nous I'avons trouve au moins aussi gros que ceux du pouee de rhomme, constant et ayant la forme d'un trois- 

 quarts d'ovoide regulier ; il possede una face veritablement articulaire, un peu convexe, et qui repond a uuc facette 

 cgalement encroutee do cartilage de la partie infericure du ouboVdo.'' (Jouni. de I'Anat. et de la Physioloo-ie viii. 

 p. 533, 1S72.) 



^ Gotthelf Fischer, 'Anatomic der Maki,' p. 154 (1S04). This ossicle is not mentioned in Burmeister's ' Beitriio-e z. 

 niih. Kentniss der Gattung Tarsius ' (1S46). 



