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FOSSILS OF THE GRAVEL SERIES: THE HORSE. 257 
f. Two lower molars, one marked Matlock Gulch, Tuolumne County, the other with no locality 
indicated. Probably belonging to the same species as the preceding. 
Equus caballus. 
a. Skull, of the size of that of the recent mustang or Indian horse of Western America. Speci- 
men entire, unchanged, and not differing in any respect from that of the living domestic horse. 
Labelled “ From auriferous gravel, thirty-five or forty feet below the surface.” * Length of skull 
from oc. condyles to incisive alveoli, 193 inches. Length of upper molar series, 6} inches. 
b. An isolated upper lateral incisor differing in no point from that of the recent horse. Un- 
changed in texture. From calcareous tufa, overlying auriferous gravel, fifteen feet in depth. From 
Texas Flat, Tuolumne County. 
ec. Two superior molars, apparently a third and a fourth, but from different individuals. Not 
fossilized and not differing from those of the recent horse. Twenty-five and twenty-nine feet below 
the surface. From Kincaid Flat, Tuolumne County. A last inferior molar from the same locality, 
and of the same general character. 
d. An inferior molar, not differing from those of the recent horse. From five or six feet of 
depth of vegetable. Columbia, Tuolumne County. 
e. Four upper molars and the fragment of another, without locality indicated. Clearly of recent 
origin. Another specimen of the same character is marked Mojave Valley. 
Fragment of the left ramus of the lower jaw containing three molars. Labelled ‘From the 
Post-pliocene of Oregon.” It belonged to a young animal, and does not differ from the correspond- 
ing part in the recent horse. The teeth consist of the last temporary molar and the succeeding 
pair of permanent molars, of which the fifth is so far protruded as to be worn at its fore part. 
Equus pacificus, n. s. 
a. An extinct species, apparently larger than any ever before indicated. The most characteris- 
tic specimen upon which it is founded consists of a second upper molar tooth nearly half worn. 
It is from Martinez, Contra Costa County, from a formation viewed by Professor Whitney as of 
Pliocene age. The tooth is well preserved, retaining its outer cementum, and appears but slightly 
changed in texture. The triturating surface in the arrangement of its enamel lines presents noth- 
ing strikingly different from that in the corresponding tooth of the recent horse, and differs from 
Equus excelsus in the same manner as the latter. Its measurements are as follows: 
Length externally, independent of the fangs : : - : . 264 lines. 
Fore and aft diameter of triturating surface. : : : : 164“ 
Transverse diameter of triturating surface. Z : : : Figg BF al ee 
Transverse diameter with cementum ; 2 F : : ; Lo) FS 
6. Three water-rolled fragments, one of an upper molar, and two of lower molars, marked from 
near Martinez, Contra Costa County, probably belong to the same species. 
ce. Another fragment of a large inferior molar, marked “ Murphy’s Diggings,” perhaps also be- 
longs to the same. 
d. Another specimen, the greater portion of a fourth or fifth lower molar, from the ‘‘ Elephant 
bed, Centerville, Alameda County,” may belong also to the same. 
Equus. 
a. A left metacarpal, of small size compared with that of the ordinary domestic horse. Length 
eight and a half inches ; breadth of extremities twenty lines : circumference at middle forty-four 
lines. Unchanged except having lost some of the bone cartilage. Labelled “ Southern California, 
sixty feet below the surface.” 
b. The lower extremity of the humerus of a small equine animal. Diameter at condyles twenty- 
* This specimen was found at Brandy City, Sierra County, at an elevation of about 2,000 feet above the 
North Yuba River. 
