494 General Notes. [ May, 
found by Mr. Baldwin at the same locality. T. scalper was prob- 
ably founded on superior incisors of P. taoénsis. 
Polymastodon attenuatus, sp. nov.—This form is represented by 
a mandibular ramus with entire dentition, of one individual, and 
by a superior incisor with portions of inferior molars of a second. 
The specific character is seen in the very compressed incisors and 
general lightness of structure of the ramus, in which it is quite 
different from the species of similar size, the P. taoënsis and P., 
latimolis (NATURALIST, April, 1885). The tubercles and propor- 
tions of the true molars are as in P. taoénsis, The apex of the 
fourth premolar is transversely fissured. The superior incisor is 
much more compressed than in that of P. taoënsis, and is more 
rapidly acuminate in its form, to the subacute apex. There are 
no facets of the internal side as in that species. The enamel covers 
almost the entire external face, and is marked by rather coarse 
parallel grooves. A groove runs along the concave edge of the 
crown, forming the edge of the enamel excepting for its distal half, 
where the enamel crosses it, and covers the internal side for its 
distal fourth. The inferior incisor is also much compressed so 
that the enamel is presented externally rather than anteriorly, 
and its cutting edge is nearly anteroposterior and not transverse, 
as in P. taoénsis. Its surface is obsoletely grooved. Length ot 
superior incisor .25; diameters do. at middle: anteroposterior 
.013; transverse .006, ngth of inferior true molars .032; 
depth of ramus at middle M. 1. .034.—£. D. Cope. 
Tue Lour Fork Miocene IN Mexico.—A considerable extent 
of tertiary deposit in the State of Hidalgo and the adjoining parts 
of Vera Cruz has been announced by Professor Antonio de Cas- 
tillo in the report of the School of Mines of Mexico for 1883. I 
recently visited the region, and obtained from the beds bones and 
teeth belonging to species of Protohippus, Hippotherium and 
Mastodon, and probably Procamelus; and Professor Castillo has 
teeth of Dicotyles. It is thus evident that the horizon is the Loup 
Fork or Upper Miocene of the North American series. This is 
by far the most southern exhibition of this formation, the nearest 
locality which I have identified with it being in New Mexico. In 
its Mexican area it occupies a tract of at least eighteen miles by 
_ six, which at present presents an extremely irregular surface. It 
i 
is excavated into numerous valleys of erosion by tributaries of 
the Tuxpan and Benados rivers, some of which are fifteen hun- 
dred feet in depth and quite narrow. The axes of the high tands 
consist of trap, which in some instances are dykes, as the lime- 
stones of palæozoic or mesozoic age lie against them inclined at 
high angles. Some of these traps inclose masses of obsidian of 
various sizes. _ tire Loup Fork formation is now not less 
us si le en 
_ than two thousand feet in thickness, as it not only fills the valleys 
but also caps the traps. Several thin beds of coal occur in it, 
both above and below the escarpments of trap; in the latter case 
$% 
