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, Miiller, and T. littoralis, Poppe ; Ophio- 

 camptus brevipes, Sars ; Mesochra lilljeboryi, Boeck ; LaopJionte 

 littorale, T. and A. Scott ; L. mohammed, Blanchard and 

 Richard ; and Dactylopus tisboides, Glaus. 



Schmeil 1 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, etc. 



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 



-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 -jointed. 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. 



3. Eciinosoma. 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. 



1 Loc. cit. p. 59. 



