1885. ] Geology and Faleontology. | 
The crowns of the superior molars support two external conical 
flattened on the external side. The entire crown is surrounded 
by a well developed cingulum, which is especially prominent 
round the external anterior cusp of the second and third true 
molars. The posterior external cusp of the last true molar is 
rudimental, and is situated well within the external line om the 
posterior border. The fourth premolar has a single external cusp, 
and the cingulum is wanting on the anterior and interior sides. 
The outline of the base of the crown of this tooth is subtriangu- 
lar; that of the first and second true molars is a half ellipse ; 
while that of the last true molar is a transverse oval as in the two 
species mentioned above. In this last respect it differs from the 
species of Mesonyx and Dissacus, where that tooth has a trian- 
- gular base. Enamel delicately wrinkled where unworn. In the 
two species of Sarcothraustes already mentioned the first and sec- 
ond true molars have a triangular outline, and there is no internal 
cingulum. 
The occiput of this species rises into an elevated transverse 
crest with an oval outline, like that of the Dinocerata. his is 
divided in front by an elevated sagittal crest. The brain cavity is 
very small. There is a preglenoid crest. 
Measurements: Length of true molars .031; diameters of Pm. 
IV, anteroposterior .O10, transverse .OI2 ; do. of M. 11, anteropos- 
terior .oI1I, transverse .016; do. of M..111, anteroposterior 008, 
transverse .015 ; elevation of occipital crest .058. | 
Phenacodus puercensis Cope. 
Periptychus coarctatus Cope. 
A BAROMETER FOR MEASURING SEPARATELY THE WEIGHT AND 
PRESSURE OF THE AIR.—The present mercurial barometer at all 
times measures, not alone the weight or pressure of the air, but 
both weight and pressure. It cannot measure either separately, 
that is, we cannot now when either pressure or weight alone has 
affected it. It is the purpose of this article to suggest a barome- 
ter that will measure alone the weight of the air and not be at all 
influenced by pressure, temperature, moisture or the sun’s or 
(from the sphere) is inserted a screw, G, with threads measuring 
one hundredth of an inch, with a large circular head, Æ, gradu- 
into divisions of one-tenth of its outside circumference, 
