1Q2 MR. W. BATESON ON [Feb. 2, 



sexes of this Gazelle, received from Herr Menges, which show well 

 the extraordinary long neck of this animal, as represented in the 

 accompanying drawing (see p. 101). No other Antelope has a 

 similar structure, which at once reminds one ot a biratte. 



9. Oryx beisa (Riipp.) ; Thomas, I. c. 



A skull and two flat skias of a female O. beisa, which is locally 

 known as " Baet." 



10. Strepsiceros kudu, Gray. 



A flat skin of this Antelope, locally called " Arrah Goder." 



11. Strepsiceros imberbis, Blyth. 



A flat skin of this Antelope, which is said to be known as " Goriali 

 Goder." 



This makes 1 1 species of Antelopes of which Capt. Swayne has 

 forwarded specimens from Berbera. 1 much regret that he has not 

 sent me accompanying notes on their habits and exact localities, but 

 he promises to do so. 



At least two other Antelopes are found in Somaliland, namely, 

 a Water-buck {Cobus sp. inc.), as mentioned by Mr. Lort Phillips 

 (P. Z. S. 1885, p. 932); and a "small red Antelope of the Klip- 

 springer kind ; horns about 2 inches long ; female hornless ; same 

 size as Alikhud : called ' Beira ' by the natives " : as described by 

 Capt. Swayne in his letters. Capt. Swayne's brother, Lieut. E. J. 

 Swayne, Bengal Staff Corps, met with this species in the Gadaburri 

 country, but was not able to shoot a specimen. It may possibly 

 be a Cephalophus. 



6. On Numerical Variation in Teeth, with a Discussion of 

 the Conception of Homology. By W. Bateson, M.A., 

 Eellow of St. John's College_, Cambridge. 



[Eeceived February 2, 1892.] 



The followhig paper is an abstract of facts regarding the Nu- 

 merical Variation of Teeth and of certain conclusions as to the 

 natureof the conception of Homology as applied to Teeth which those 

 iacts have suggested. The observations concerning teeth form part 

 of an investigation of the Variation of Multiple Parts in general, and 

 I hope that before long the results of this work will be published in 

 a complete form by Messrs. Macmillan, to whom I am much 

 indebted for leave to use the blocks with which this paper is illus- 

 trated. 



In an abstract it is clearly impossible to set forth the precise 

 value and significance of the Study of Variation as a clue to the 

 problems of Descent ; but since by most this subject is wholly 

 neglected, it may be well to state in the fewest words why it is that 



