908 General Notes. [ December, 
vertical; but as the coal nearer the surface becomes exhausted, 
the mines must go deeper and become more expensive, — Proceed- 
ings of the American Association for Advancement of Science, 1879. 
THE NorTHERN WasATcH Fauna.—The following species have 
been received from Mr. Wortman from the beds of the Wind 
er group, subsequent to the publication of my last notice of his 
discoveries (1) Esthonyx spatularius, sp. nov. Represented by 
five molar and premolar, and two incisor or canine teeth, appar- 
ently belonging tq one individual. These are about the size of those 
of E. bisulcatus, but present several differences of detail. Thus the 
basin of the heel of the last inferior molar is not obliquely cut off 
by a crest which extends forwards from the heel, but is surround- 
ed by an elevated border, which rises into a cusp on the external 
side. The incisor-canine teeth are more robust than those of 
E. bisulcatus, one of them especially having a spoon-shaped crown, 
with the concave side divided by a longitudinal rib, on which the 
enamel is very thin. The enamel descends much further down on 
the external than the internal side of these teeth. The rodent- 
like tooth does not accompany the specimen. Length of base of 
läst inferior molar, .009; width anteriorly, .005 ; length of crown 
of canine-incisor No. 1, .009; width of do. at base, .005; length of 
crown of second canine-incisor at base, .o12; width of do., .006. 
(2) Didymictis leptomylus; represented by the posterior three in- 
ferior molars. These indicate a species of smaller size than the 
D. protenus, with the tubercular molar relatively narrower, and 
perhaps longer. The anterior part of the latter has the three 
cusps well defined and close together, and behind them is an ob- 
lique longitudinal cutting edge. The middle of the posterior 
margin rises into a tubercle. The anterior cusps of the tubercular 
sectorial are elevated ; the heel has a strong external cutting edge 
and internal ledge. Length of tubercular sectorial, .009 ; width 
of do., .005 ; length of tubercular, .007; width of do. in front, 
.0035. (3) Hyopsodus speirianus, sp.nov. Founded on a portion , 
of a mandibular ramus supporting the last three molars in perfect 
preservation. It is distinguished by its very small size, since it 
is considerably less than the Æ. vicarius (H.? minusculus), and 
by the equality in size of the molars. The heel of the third molar 
1! NATURALIST, Oct. (Sept.), 1880, p. 745. 
