3 1 8 SCOTT. [Vol. V. 



preserved spine to show whether a metacromion was present. 

 The glenoid border is much thickened, and the coracoid border, 

 so far as preserved, is quite thin and sharp. The course of the 

 former indicates that the blade of the scapula was proportion- 

 ately broader than in the horse, and the neck is much more 

 contracted. 



The fragment of Anchitherium scapula which Kowalevsky 

 figures (PI. I., Fig. 37), agrees very closely with that of Meso- 

 hippus, the only observable difference being that the coracoid is 

 somewhat more massive. " La spina scapula: commence plus 

 loin du bord glenoi'dale que dans les Paleotheriums et monte 

 presque perpendiculairement, avec une legere inclinaison en 

 dehors ou en arriere ; cette inclinaison de la spina scapula en 

 dehors est tres caracteristique pour tous les imparidigites, elle 

 s'explique par le fait que cette portion de l'omoplate sert 

 d'insertion aux grands muscles qui aide a tourner le bras (M. 

 cucullaris, ce muscle est insignifiant chez le cheval). Chez les 

 rhinoceros cette partie de la spina donne encore un processus 

 en arriere pour augmenter la superficie de l'insertion muscu- 

 laire. Avec la reduction des mouvements lateraux ce caractere 

 commence a se perdre, et chez le cheval tous les mouvements 

 lateraux des extr^mites sont reduits a leur minimum, la spina 

 scapula perd les caracteres perissodactyles et fait un pas vers 

 les ruminants ; elle s'incline dans sa partie anterieure en dedans " 

 (No. 25, p. 5). 



It is of interest to observe that the scapula of E. caballus 

 differs from that of E. asinus in very much the same way as 

 does the scapula of the camel from that of the llama. 



The humerus (PI. XXIIL, Figs. 19-22) of MesoJiippus is rela- 

 tively short ; the head is flattened and projects very strongly 

 backward ; when the bone is placed in the vertical position, the 

 head presents more posteriorly than superiorly. The external 

 tuberosity is very large, extending across nearly the entire ante- 

 rior face of the bone and ending in a stout, blunt hook, which 

 overhangs the bicipital groove. This tuberosity is divided into 

 two portions, a smaller external one with smooth surface, and a 

 larger rugose internal one. The inner tuberosity is well devel- 

 oped, and incloses, with the outer, a very deep and narrow bi- 

 cipital groove, which is situated at the antero-internal angle of 

 the head. In none of the specimens which I have examined is 



