chap, xiii.] DIGITS I KITTIWAKE, ELEPHANT, &C. 397 



this country and in N. Atlantic has no hallux, but only a small 

 knob without a nail in its place. No variation in respect of this 

 digit is recorded 1 . Birds not distinguishable from the Atlantic 

 Kittiwake occur in the North Pacific, but amongst these Pacific 

 specimens birds are found occasionally as rarities having a hallux 

 "as large as it is in any species of Larus" (CoUES, p. 646). This 

 feature also exhibits gradations. Specimens are described by 

 Coues and also by Saunders having the hallux including the 

 nail '2 in. long, with a perfect claw. These are given as extreme 

 examples. Saunders remarks that this hallux is small for the 

 size of the bird, stating that another species of similar size, L. 

 canus, had a hallux "5 in. long. Of these specimens of R. tridac- 

 tyla from Alaska one had the nail of the hallux developed, though 

 less so than in the extreme case. Saunders states further that the 

 variation is not always equal in extent on both feet of the same 

 individual : he considers that the extreme form is probably rare 

 and local. Coues, E., Birds of North- West (U. 8. Geol. Surv. 

 Terr.), 1874, p. 646; and Saunders, Howard, P. Z. 8., 1878, pp. 

 162—64. 



ill. Rissa brevirostris : a species from the N. Pacific distinct from 

 R. tridactyla shews a similar variation in the development of the 

 hallux, though in a smaller degree. A specimen has no claw on 

 right hind toe and only minute speck on left ; another has no 

 hind nail whatever ; another has small black nails of unequal size 

 on the two hind toes. Saunders, H., I. c, p. 165. 



;12. Erinaceus. E. europaius has a large hallux, while in E. diadema- 

 tus it is only 4 mm. in length, and in E. albiventris it is normally absent 

 in adults. An adult female E. albiventris had a minute hallux in 

 the left hind foot, represented by a claw and ligamentous structures, 

 the phalanges being absent 2 . In a female a few months old a minute 

 hallux with usual number of phalanges was present on both sides. 

 The presence or absence of a hallux has often been considered a suffi- 

 cient ground for the formation of a new genus. Dobsox, G. E., 

 P. Z. S., 1884, p. 402. 



13. Elephas. In both the Indian and. African elephant the 

 number of digits represented by bones is five, both in the fore and 

 the hind foot. The number of hoofs differs in the two species. 

 The African elephant has normally four on the fore foot and three 



character, as the same feature occurs as is well known, not only in certain genera 

 of other allied families (such as Alcedinida? and Picidas), but even in a genus of 

 Oscines (Cholornis), in which group the foot-structure is generally of a very uniform 

 character." Sclater, P. L., Monograph of the Jacamars and Pujf'-Birds, 1879 — 82, 

 p. 50. 



1 Mr A. H. Evans has called my attention to a recent paper by Clarke (Ibis, 

 1892, p. 412) giving an account of a minute rudiment of the hallux in embryos of 

 B. tridactyla from Scotland. 



2 Compare facts as to the loss of the hallux in Mungooses (Herpestidre), Thomas, 

 0., P. Z. S., 1882, p. 61. 



