CRANIOLOGICAL DIFFERENCES BETWEEN THE ASS AND THE HORSE. 405 
Later J. C. Forsyth Major,* Mme. Pavlow,t Nehring,t Kowalewski,§ and 
Woldrich|| touched more or less at length upon the relation of the skulls of the 
ass and horse. Still later some of the French investigators discussed these very 
different and partly contradictory criteria, thus Duges,{{ Monfalet,** and before 
all X. Lesbre, ff the veterinary anatomist of Lyons. 
I will here state briefly those characteristics on which these authors lay 
the most stress: 
According to Owen, in the upper series of grinders the degree of oblique attri- 
tion of premolar 2 causes its working surface to appear more produced and acute 
anteriorly than in less worn and more evenly worn specimens. Besides the general 
inferiority of size of teeth, molar 3 is relatively less than in Equus caballus and 
is not bilobed behind: the outer channels are more evenly curved or concave; 
and as the same character prevails in the inner enamel-wall of the lobes these are 
more regularly crescentic in shape. The longitudinal ridge is relatively narrower. 
A slight excess of fore-and-aft over transverse diameter of grinding surface is 
recognizable in the ass—such excess not being seen in the permanent grinders, 
premolar 3 to molar 2, of the horse. 
Rtitimeyer regards as a constant characteristic for the teeth of the ass, as 
compared with the horse, the relatively slight length of the foremost as well as of 
the hindmost molar in both the upper and lower jaws. Also he considers the 
premolars and molars in the ass to be shorter than in the horse; the foremost 
premolar tooth is strikingly short. Riitimeyer declares irrelevant the circum- 
stance mentioned by Owen that molar 3 superior is less bilobed in its posterior 
circumference than in the horse. He ascribes to the ass, at least in the teeth 
of the upper jaw, more oblique enamel plications than occur in the horse, but 
he remarks that one can not disregard the fact that all these characteristics, in so 
far as they concern construction of the teeth, recur in very old horse teeth; there- 
fore, in the earlier stages of abrasion, the teeth of the ass show the characteristics 
which correspond to the deeper parts of the tooth lying nearer to the root. In 
addition to this is the relatively small extent of the toothless part between pre- 
molars and canines, as well as the slight width of the incisor crown. Thus, in 
the ass the whole construction is more compact and crowded. 

* J]. C. Forsyth Major, Beitrage z. Geschichte d. fossilen Pferdes, insbesondere Italiens. Abhandl. 
Schweiz. paleontol. Gesellsch., vr and vu, 1880. 
+ Marie Pavlow, Etude sur I’histoire paléontologique des Qngulés. Bull. Soc. Imp. d. Naturalistes, 
Moscow, 1889. 
t Alfred Nehring, Fossile Pferde aus deutschen Diluvialablagerungen, Landw. Jahrb. 1884, Bd. 13, 
Ppp. 149 et seq. 
§ Waldemar Kowalewski, Monographie der Gattung Anthracotherium Cuv. u. Versuch einer nattir- 
lichen Klassification d. fossilen Huftiere. (Paleontographica, N. F.u, 3, xxi.) Sur lAnchiterium Aur- 
elianense Cuy. et sur l’histoire paléontologique des Chevaux. Mém. de I’ Académie Imp. d. Sciences, St.- 
rar 8 Vile SDeLic ute Da 59 ko 73. 
|| J. N. Woldrich, Beitrage z. Fauna der Breccien und anderer diluv. Gebilde Oesterreichs. Jahrb. 
k. k. Geol. Reichsanstalt, Bd. xxx, Heft 4. Wien, 1882. 
q A. Dugés, Paralelo de los craneos de caballo i de asino. Guanojuato, 1898. Actes Soc. Scient. d. 
Chilis tavillppay7. 7 
«TD, Monfalet, tee complémentaire sur la communication de M. Dugés. Jbidem, pp. 79, 80. 
Ths. Lesbre; Observations sur la machoire et les dents des Solipédes. Bull. Soc. d’ Anthropologie 
de Lyon, t. XI, 1892, pp. 49 e¢ seq. 
