MUSEUM OF COMPARATIVE ZOOLOGY. 



81 



tentaculum is short, but broad and thick, and the fibular facet is high, but short 

 and narrow. As compared with the calcaneum of recent deer, that of Blasto- 

 meryx has less antero-posterior diameter below, and a somewhat less thickened 

 tuberosity at the free end, quite unimportant differences. The cuboid and 

 navicular are firmly co-ossified, as in Palceomeryx and all existing Pecora ; these 

 bones are quite low, and the navicular rises but little in front to fit the distal 

 groove of the astragalus, but on the postero-internal side it sends up a strong 

 and high process, which makes the astragalar facet very deeply concave ; dis- 

 tally the navicular shows two facets, a large one for the compound cuneiform, 

 and a much smaller one for the entocuneiform. On the distal surface of the 

 cuboid, besides the large facet for mt. IV., is seen a minute, oblique infero- 

 lateral one, obviously for a rudimentary fifth digit. The only other tarsal 

 bone preserved in the specimens is the compound cuneiform, which is rather 

 low, narrow, and deep ; in front it is nearly on a level with the cuboid, but be- 

 hind descends somewhat below it, and thus affords a lateral attachment to 

 mt. IV. The presence of a distinct entocuneiform is demonstrated by the 

 facets for it upon the navicular and cannon-bone. 



The metatarsus presents some features of much interest. Rosenberg (Zeitschr. 

 f. wiss. Zool., Bd. XXIII.) has shown that in the sheep embryo there are at 

 one stage four complete metatarsals ; he states, however, that the lateral ones 

 are ultimately absorbed. In Blastomeryx, as in Amjohitragulus, and probably 

 all existing Pecora and Tylopoda, there are at least three elements which enter 

 into the formation of the poste- 

 rior cannon-bone ; viz. mt. III. 

 and IV., and the proximal por- 

 tion of mt. II. The latter, though 

 ankylosed with mt. III., shows 

 its limits distinctly ; it has a 

 small facet for the entocunei- 

 form, and ends below in a point. 

 Mt. V. was obviously present, as 

 upon the postero-external side of 

 the cannon-bone there is a shal- 

 low groove, and upon the cuboid, 

 as already stated, there is a small 



facet for the head of it. An examination of the metatarsus of a modern rumi- 

 nant seems to show that the portion articulating with the entocuneiform is the 

 head of nit. II. ; whether mt. V. be also present is more difficult to decide, but 

 in existing forms there is no portion which can be identified with it, while in 

 Blastomeryx, though undoubtedly present, it does not coalesce with the cannon- 

 bone. There is nothing in any of the specimens to indicate that any portion 

 of the distal ends of the lateral metatarsals were retained, though doubtless 

 phalanges were preserved, as in the deer. 



In this brief, but fairly comprehensive review of the osteology of Blastomeryx, 

 we have seen nothing which can be opposed to the view expressed by Professor 



vol. xx. — no. 3. 6 



A. B c 



Figure 9. — Proximal end of posterior cannon- 

 bones X §, internal view; A. Amphitragulus; 

 B. Blastomeryx; C. Aniilocapra. 



