Geology. 381 



horizontal position of the pelvis " Esnea " would show were the 

 skeleton properly mounted. As it is, the back is so highly arched 

 that the zygapophyses are pulled apart. 



(3.) The short tail is a distinctive feature, "Nimr" having six- 

 teen vertebrae compared with the eighteen of a draught horse, 

 while " Esnea " has but thirteen and the tail is seemingly 

 complete. 



(4.) The fourth character, that of a complete shaft to the ulna, 

 "Esnea" does not show, for with her the shaft is discontinuous 

 for about 65 mra , although a fractured end implies that the actual 

 break in the continuity of the bone may have been less. 



(5.) The Arab skeleton is noted for the great density of the 

 bone. This is not especially true of " Nimr." Whether or not 

 it is true of "Esnea" has not been ascertained. 



(6.) The skull of "Nimr" has a large brain case, prominent 

 orbits, a broad forehead, and a " dish profile." That of "Esnea" 

 agrees except that the profile is not dished. 



(7.) The development of the sagittal crest in " Nimr," as well 

 as the fossse for the insertion of the masseteric muscles in the 

 angular region of the jaw, are probably more exaggerated than 

 in "Esnea" as a sexual character. The slender, tapering jaw is 

 characteristic of both individuals. 



(8.) "Esnea" shows the slight depression in the malar region 

 in front of and below the eyes, to which Lydekker calls attention 

 as characteristic of the skulls of several thoroughbreds. This 

 "Nimr" does not show. 



Finally, Osborn says : "Altogether in my opinion these osteo- 

 logical characters justify the separation of the Arab as a distinct 

 species (Equus africanus Sanson), of distinct origin and from 

 wild ancestors very different from those of the northern horse." 



R. s. L. 



5. Eiszeit unci Urgeschichte der Menschen ; von Dr. Hans 

 Pohlig. Pp. 141. Leipzig, 1907 (Quelle & Meyer). — This is 

 a valuable little book recently published by the well-known 

 authority on the Pleistocene faunae of Europe. 



6. Physikalische Kristallographie vom StandpunJct der 

 Strukturtheorie ; von Ernst Sohereeldt. Pp. vi, 131, mit 122 

 Abbildungen im Text und auf eingeheften Tafeln. Leipzig, 1907 

 (Chr. Herm. Tauchnitz). — This compact volume will be found 

 useful and interesting by those desirous of obtaining a knowledge 

 of the modern theory of molecular structure and the crystal- 

 lographic and physical relations connected with it. The matter 

 is presented after the manner of Sohncke, and is liberally illus- 

 trated by photographs from models, which will be helpful to the 

 student. The application of the theory of structure to the 

 different aspects of crystallographic physics, as the etching figures, 

 the phenomena of rotatory polarization, etc., are well presented in 

 the latter part of the work. 



Am. Jour. Sci.— Fourth Series, Vol. XXIV, No. 142.— October, 1907. 

 26 



