116 BULLETIN 99, UNITED STATES NATIONAL MUSEUM. 
our trinomial nomenclature. They are for the most, it would seem, 
merely such ordinary ‘‘individual variations” as exist among all 
mammals, and such as are especially conspicuous among those bearing 
horns or antlers. The growth of horn is dependent in a measure 
rarely appreciated upon the vitality of the individual; and the effects 
of climatic conditions and other causes, from season to season, with 
the resulting variations in the food supply, are practically unknown. 
Several more ‘‘forms,’’ based on characters and measurements of 
skulls and horns, and each differing from any named “‘race,’’ could be 
described from our Loita series alone. The attempts to account for 
certain peculiarities in horn shape in some individual animals by 
classing the specimens as mixtures (“‘Bastarde’’) between two or 
more named races seem little less than absurd. It is unusual to find 
two pairs of horns even approximately alike; and in a large series like 
our Loita and Southern Guaso Nyiro collection of Thomson’s gazelles, 
there is wide diversity between the extremes of variation. This 
obtains not only for horns, but for shape and relationships of certain 
variable bones of the skull as well. 
I am now able to recognize in the National Museum collection four 
apparently valid geographical races of this gazelle. One of these, 
the Athi and Kapiti Plains form, was ignored by Heller; and speci- 
mens representing the fourth race, which I have referred to Gazella 
thomsonit. ruwane Knottnerus-Meyer, have reached the museum 
since the time of Heller’s work. Because of lack of material from 
certain regions I have not synonymized names for several of the 
described forms. It is probable that some of these may be recogniz- 
able for valid geographic races, although J feel quite confident that 
the number of names is far too great. Some of these names are 
discussed under other subspecies, but seven, from the Kilimanjaro 
region south and westward to the Wembere Steppe, and not mentioned 
elsewhere, may be listed here as a matter of record. These, with 
their type localities, are: Hudorcas schillingst Knottnerus-Meyer,' 
between Lake Natron and Kilimanjaro, German Hast Africa; E. ndji-. 
riensis Knottnerus-Meyer,? West Ndjiri Swamp, German East Africa; 
E. sabakiensis Knottnerus-Meyer,? East Ndjiri Swamp, German East 
Africa; E.. wembaerensis Knottnerus-Meyer,* Wembere Plains, German 
East Africa; E. manyarae Knottnerus-Meyer,’ Lake Hohenlohe, south 
of Lake Eyasi, German East Africa; EL. thomsona macrocephala 
Zukowsky,® southern Wembere Plains, German East Africa; and 
1 Sitz.-ber. Ges. nat. Freunde Berlin, 1910, No. 3, p. 113. March, 1910. 
2 Sitz.-ber. Ges. nat. Freunde Berlin, 1910, No. 3, p. 115. March, 1910. 
3 Sitz.-ber. Ges. nat. Freunde Berlin, 1910, No. 3, p. 115. March, 1910. 
4 Sitz.-ber. Ges. nat. Freunde Berlin, 1910, No. 3, p. 119. March, 1910. 
6 Sitz.-ber, Ges. nat. Freunde Berlin, 1910, No. 3, p. 120. March, 1910. 
6 Archiy f. Nat., 80 Jahrg., Abt. A, Heft 1, p.68. 1914. 
