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Show Much smaller than the last species, the costulae more distant, and densely marked with minute spirals. I can find no trace of these latter in D. skeati, but the single specimen was not taken alive. G eorissa m on ter osa t ia x a Godwin-Austen & Nevill. Geot'issa monterosatiana Godwin-Austen & Nevill, P. Zool. Soc. 1879, p. 729, pi. lix. fig. 6. Hab. Perak. EXPLANATION OF PLATE X X . Figs. 1, 2. Pteroci/clos subalatus, p. 195. 3. Diplommatina skeati, p. 198. 4, 5. Opisthnstoma anncindalei, p. 198. 6 ,7 ,8 . Rhiostoma jalorensis, p. 196. 9, 10. Bhapliaidus perakensis, var .jalorensis, p. 197 11,12. Rhaphaulus ascendetis, p. 196. 13,14,15. Lagochilus kobelti, p. 191. 16. Diplommatina laidlawi, p. 198. 1 7,18 ,1 9 . Ditropis cavernce, p. 195. 3. The Significance of the Callosities on the Limbs of the Eguidce. By R. L y d e k k e r , F.Z.S. [Received Februarj' 5, 1903.] The question as to what structures in other mammals are represented by the callosities on the inner sides of all the limbs of the Horse, and those of the hind-limbs of the Kiang, Ass, and Zebras, is one which has attracted the attention of many naturalists, nearly all of whom appear to be in accord in regarding them as vestigial structures. The late Sir W. H. Flower, for instance, in his work 4 The Horse ' expressed the opinion that these structures are degenerate glands; pointing out at the same time that the so-called ergot on the hinder aspect of the horse's pastern appears to represent one of the pads, or cushions, which are still functional in the foot of the Tapir. In his volume on " Mammalia " in the ‘ Cambridge Natural History' 1, of which the preface is dated February 1902, Mr. Beddard gives a qualified support to this gland-theory ; stating in one passage that the equine front callosities probably correspond to the carpal glands of several other mammals, although on another page their glandular nature is questioned. In an apparently later communication 2 the same gentleman suggests that the callosities on the fore-limbs of the Equidce may represent a carpal sense-organ, vestiges of which he believes to survive in the carpal bristles of the Dassies. Hie degeneration of such an organ would, it is urged, very likely result in the formation of structures resembling those under consideration. 1 Pp. 12, 13, and 240. 2 Proc. Zool. Soc. 1902, i. p. 135.- I am indebted to Mr. Beddard himself for directing my attention to this passage. 1903.] OX THE CALLOSITIES OX THE LIMBS OF THE EQUID/E. 199 |
