62 CRUSTACEA——COPEPODA CHAP. 
distributed in the Mediterranean and northern seas, exhibits the 
structure of a typical Harpacticid, while Fig. 29 shows the form 
of the first antenna in the male. 
Several fresh-water representatives of these free-living families 
occur. The genus Cyclops (Cyclopidae) is exclusively fresh-water, 
while many Harpacticidae go up into brackish waters: for 
example on the Norfolk Broads, Mr. Robert Gurney has taken 
Tachidius brevicornis, Miller, and 7. littoralis, Poppe; Ophio- 
camptus brevipes, Sars; Mesochra lilljeborgi, Boeck; Laophonte 
littorale, T. and A. Scott; JZ. mohammed, Blanchard and 
Richard; and Dactylopus tisboides, Claus. 
Schmeil! gives the following scheme for identifying the 
fresh-water Cyclopidae and Harpacticidae (see diagnosis of 
Centropagidae on p. 59) :— 
Fam. 1. Cyclopidae.—The cephalothorax is clearly separated 
from the abdomen. The first antennae of the female when bent 
back do not stretch beyond the cephalothorax ; in the male both 
of them are clasping organs. The second antennae are without 
an exopodite. The fifth pair of limbs are rudimentary, there is 
no heart, and the female carries two egg-sacs. 
Cyclops.—Numerous species, split up according to segmentation of 
rudimentary fifth pair of legs, number of joints in antennae, ete. 
Fam. 2. Harpacticidae.—The cephalothorax is not clearly 
separated from the abdomen. The first antennae are short in 
both sexes, both being clasping organs in the male. The second 
antennae have a rudimentary exopodite. The fifth pair of limbs 
are rudimentary and plate-shaped; a heart is absent, and the 
ege-sacs of the female may be one or two in number. 
1. Ophiocamptus (Moraria).— Body worm-shaped ; first antennae of 
female 7-jointed, rostrum forming a broad plate. 
2. Body not worm-shaped ; first antennae of female 8-jointed, rostrum 
short and sharp. 
(#) Endopodites of all thoracic limbs 3-joimted. The first 
antennae in female distinctly bent after the second joint. 
Nitocra. : 
(b) Endopodite of at least the fourth limb 2-jointed ; first 
antennae in female not bent. Canthocamptus. 
Ww 
3. Ectinosoma,—Body as in 2, but first antennae are very short, and 
the maxillipede docs not carry a terminal hooked seta as in 1] and 2. 
U goc. cits 1p. 169: 
