212 The American Naturalist. [February, 
them, they may be able to detect further evidence, where, without this 
suggestion, they might not look for it. 
On CERTAIN PECULIAR STRUCTURAL FEATURES IN THE FOOTHILL 
REGION OF THE Rocky MOUNTAINS NEAR DENVER, CoLorapDo. Geo. 
H. Eldridge, Washington, D. C.—The paper describes a type of geo- 
logical structure discovered by the writer, which may prove of common 
occurrence along the base of the Rocky Mountains. The type con- 
sists in a succession of nonconformities appearing one after another at 
various geological horizons, the explanation of which is found in the 
forces acting in the general uplift of the Colorado Range, from which 
have been developed certain secondary forces, which have, from point 
to point,jbrought about the elevations upon which the nonconformities 
depend. 
ON THE INTRUSIVE. ORIGIN OF THE TRIASSIC TRAPS or NEW JERSEY ; 
WITH SPECIAL REFERENCE TO WaTCHUNG Mountains. Frank L. Na- 
son, New Brunswick, N. J.—That these traps are intrusive in their 
origin is proved: I. By the peculiar monoclinal structure of the sand- 
stones, which are produced by longitudinal fractures extending parallel 
(a) to the major axis of the trap ridges, and (b) to the major axis of 
the Archzean region. II. By the finding of Zstheria ovata in repeated 
lines along the Delaware River, and in lines reaching N. E. and S, W. 
across the State. III. By the lines of cross-fracture extending N. W. 
and S. E. across the formation, which are proved (a) by showing a 
repetition of the slates and gray sandstones at Weehawken and Shady 
Side ; (b) by showing that the Pequannock River flows in a fault ; (c) 
by showing that the streams of the Archæan region flow in faults par- 
allel to the “ crescents ”’ of the trap. 
Association of American Anatomists.—The second annual 
meeting was held at the University of Pennsylvania, Thursday, De- 
cember 26, 1889. The following communications were made: Pres- 
ident’s Address; by Joseph Leidy, M.D., of Philadelphia, Pa. Ad- 
dress of the Chairman of the Executive Committee ; by Harrison 
Allen, M.D., of Philadelphia, Pa. Muscular Anomalies of the Infra- 
Clavicular Region; by Frank Baker, M.D., of Washington, D. C. 
On Plant Anatomy and Physiology ; by W. P. Wilson, M.D., of Phil- 
adelphia, Pa. Brief Remarks on the Form and Probable Function of 
the Blood Plaque, with slides and photographs; by George T. Kemp, 
. Presentation of Histological Specimens ; by George A. Pier- 
sol, M.D., Philadelphia, Pg. ‘The Supra-Sternal Rib; by D. S. Lamb, 
M.D., of Washington, D. C. A Demonstration ; by Horace Jayne, 

