ENTOMOSTRACA OF MINNESOTA. 145 
notes Daphnia galeata, D. pellucida and D. pulex; also a species of Bos- 
mina, Eurycercus lamellatus and Leptodora hyalina. 
- <A. E. Birge was the first to systematically study Cladocera in 
America, and his Notes on Cladocera furnished a basis upon which to 
build. A few notes were published by the writer a little later. 
A few additional notes and descriptions of new species were pub- 
lished in the Eleventh Annual Report of the Minnesota Geological and 
Natural History Survey. 
Professor Birge published other notes in the Medical Journal and 
Examiner of Chicago, which I have not seen. . 
Professor Forbes of Normal, [1l., in an article in the American 
Naturalist, July, 1882, adds a number of facts and one new species. 
In addition to the above, a figure of Sida was printed in one of 
Hayden's Survey Reports, and some account of the Cladocera of Lake 
Michigan was given by B. W. Thomas, I believe, in one of the official 
reports of the Chicago Water Commission. 
Since the publication of the first edition several papers by Profes- 
sor Birge, Professor Turner and the writer seem to be the only ones 
requiring notice. 
KEY TO THE ORDER CLADOCERA. 
I. Body enclosed in a bivalve shell. Mandibles truncate below. Maxillee 
distinct, spiny. Thoracic ganglia discrete. (Sub-order Calyptomera. ) 
a. Six pairs of feet, similar, foliaceous, all distinctly branchiate. 
(Tribe Ctenopoda.) 
* Swimming antenne with two unequal rami, intestine simple. 
Family Sididze, 146 
** Swimming antenne simple, elongate cylindrical (in the male 
prehensile); intestine with two lateral dilations. 
Family Holopedide, 151 
b. Five (or six) pairs of feet, the anterior pair more or less prehensile 
and destitute of branchix. (Tribe Anomopoda.) 
* Rami of antenne three- and four-jointed; five pairs of feet, the 
last with a curved appendage guarding the branchial sac; 
antennules of the female short, one-jointed. 
Family Daphnidee, 152 — 
** Six pairs of feet; antennules elongated, many jointed. 
Family Bosminidz, 206 
*** Antennules of female elongated, but one-jointed; intestine 
simple or convolute. . : . Family Lyncodaphnidz, 209 
**** Antenne with both rami three-jointed; intestine convolute, 
with abdominal but no anterior coeca. Family Lynceid ze, 224 
II. Body without or nearly destitute of a bivalve shell; feet not branchiate, 
spiny; anterior thoracic ganglia in one mass. (Sub-order Gymnomera.) 
a. Abdomen curved, terminating in two long stylets. 
Family Polyphemidze, 266 
b. Abdomen straight, ending in short claws. Family Leptodoridz, 268 
