VOL. XXXIV, NO, 398” FEBRUARY, 1900 
THE 
AMERICAN 
NATIURAEISET 
A MONTHLY JOURNAL 
DEVOTED TO THE NATURAL SCIENCES 
IN THEIR WIDEST SENSE 
CONTENTS 
I. The Angulation of the Limbs of Proboscidia, Dinocerata, and other 
Quadrupeds in Adaptation to Weight . HENRY FAIRFIELD OSBORN 89 
II. The Specific Gravity of Some Fresh-Water Animals in Relation to 
their Habits n STEPHEN R. WILLIAMS 95 
III. The Mosaic of Single ic Twin Cones in in the Retina of Fishes 
CARL H. EIGENMANN and GEORGE DANIEL SHAFER 109 
IV. Note on the Genital Organs of Zaitha THOMAS H, MONTGOMERY, JR. 119 
V. Willey on the Enteropneusta . . MAYNARD M. METCALF 123 
VI. Synopses of North-American Invertebrates. VII. The Cyclome- 
topous or Cancroid Crabs of North America . MARY J. RATHBUN 131 
VIL Reviews of Recent Literature: Anthropology, Anthropological Notes — 145 
ind Biology, A Study of Heredity among the Deaf » Blatchley's. 146 
leanings fro! 
Tunicates of Pribilof Islands, Physiology of the Cephalopods, Excretion 
in Mollusca, The Heart of Anodonta, Grafting and gnome E in. 
Hydromedusz, Regeneration in Grafted Tissue, Note — Geology, The 156 
Absaroka Range of the Rocky Mountains —Petrography, Experimental 160 
Petrography, Notes : prot 
VIII. Publications Received 163 
BOSTON, U.S.A. 
GINN & COMPANY, PUBLISHERS 
9-13 TREMONT PLACE 
New York Chicago . London — 
70 Fifth Avenue 378-388 Wabash Avenue 37 Bedford Street, Strand. 
I sdoswd! nd the Pub 
