VoL. XXXIII, No. 388” APRIL, 1899 
THE 
AMERICAN 
NA TURAL IS 
A MONTHLY JOURNAL 
DEVOTED TO THE NATURAL SCIENCES 
IN THEIR WIDEST SENSE 
CONTENTS 
PAGE 
I. Four Categories of Species . ga ee wet eos 0. F. COOK 287 
II. Vacation Notes. I. Notes on the Califo 
ree es DOUGLAS H. CAMPBELL 299 
III. The Senara of the PES as a Function of the Central 
Nervous Syst Professor HEINRICH OBERSTEINER 313 
IV. Editorial daai b: yee re Musée du Congo, A Botanical Calendar, 
The Beiträge zur Biologie der Pflanzen, “ Natural Science” 331 
V. Reviews of Recent Literature: Anthropology, African Skulls, Ceremonial 333 
Stones — Zod/ogy, Adriatic Sponges, Revised Classification of the 3384 
Unionidz, Rotifera and Protozoa of the Illinois River, Diurnal Migration 
of the Plankton, Plankton of the Oder, Nematode Parasites, Origin and 
Development of Sense Organs, Eckstein’s Zoologie, Crustacea of Nor- 
way, Japanese Pulmonates, Brooding in Frogs, Marine Mollusca in the 
Suez Canal, Hertwig’s Summaries in Systematic Zodlogy, Fishes of 
Ecuador, A New Type of Shark, American Gordiacea, Development 
of the Eel — Botany, A New School Botany, REEN iamar 345 
Schumann’s Monograph of the Cactacez, Sargent’s Silv ematic 
Plant Anatomy, Botanical Notes — Geo/ogy, The hain of peda 50 
Petrography, Experimental essay Ae The Basic Rocks of Ivrea, The 352 
asalts of Steiermark, Petrographical Not 
VI. News 355 
VII. Correspondence: The True Function of the University of the United 
States, SUSANNA PHELPS GAGE — GaAskell’s Theory of the Origin of 358 
Vertebrates from Crustacean Ancestors, Professor WILLIAM .PATTEN 360 
VIII. Publications Received 370 
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