164 THE AMERICAN NATURALIST. (VoL. XXXIII. 
Classification of the Centropagide.' 
F. W. Schacht has given us a revision of the North American 
species of this family of Copepoda. On account of the widespread 
interest in this group among students of organisms in potable water, 
and of the food of fresh-water fishes, we reproduce here in tabular 
form the criteria for distinguishing the family and also its con- 
stituent genera. 
ay. Division of the body into cephalothorax and abdomen between the 
thoracic segment bearing the fifth a of feet and the segment bear- 
ing the genital apertures. GYMNOPLEA. 
4, In male: Anterior antenne symmetrical or nearly so; and its 
secondary sexual characters not confined to peculiarities in 
structure of trunk, the antenna, the fifth pair of feet, and the 
abdomen. Marine. AMPHASKANDRIA. 
č, In male: Anterior antenne unsymmetrical and secondary sexual 
characters generally confined to points enumerated above in 
(4;)- HETERARTHRANDRIA. 
cy Rostrum present. 
d, In female abdomen 3 or fewer segments; antennz 
with 24 or fewer joints. Male with inner ramus 
of fifth feet rarely rudimentary. Marin 
Family Pontelttle: 
d, In female abdomen never fewer than 3 segments ; 
antenne never fewer than 24 segments, In male, 
fifth pair feet are grasping organs. 
Family Centropagide. 
ca Rostrum wanting. Family Candacide. 
a;. Division of the body into anterior and posterior parts in front of last 
(fifth) thoracic segment. ODOPLEA. 
Subdivisions of the family Centropagide. 
äı. Thorax 6-jointed. Subfamily CENTROPAGINA. 
az. Thorax 5-jointed. 
bı. Fifth pair feet degenerate; inner ramus, o-1 jointed; puter 
ramus, 1-3 jointed. Abdomen of 9, 3-jointed. 
Subfamily TEMORINA. 
ł Schacht, F. W. The North American Species of Diaptomus, Bull. ZH. 
State Lab. Nat. Hist, vol. v (1897), Art. 3, pp- 97-208, Pls. XXI-XXXV. The 
North American Centropagide belonging to the Genera Osphranticum, Lim- 
nocalanus, and Epischura, Bull. Jli. State Lab. Nat. Hist, vol. v (1898), Art. 4, 
pp. 225-269 
