288 HISTORY OF BRITISH CRUSTACEA. 



occurs as a recent species living in the Gravesend ditches, 

 where Mr. Pickering " found it in great numbers, attached 

 to the cases of caddis- worms, in a ditch which runs on the 

 land side of the Thames bank, between Gravesend town and 

 Coal-house Point, near an old mill ; the water flowing into, 

 and not from the Thames, except at high tides." 



Fam. CYTHERIDM 



Two pairs of antennas, the upper not furnished with the 

 pencil of long filaments. Feet three pairs. 



Gen. 157. CYTHERE, Muller. 



Eeet not enclosed in the shell, three pairs ; abdomen 

 short. One eye. Carapace valves in front and behind, 

 usually ornamented with a marginal series of fine spines. 

 It is chiefly in sea- water that the species of this genus are to 

 be found, especially in the little pools among rocks on the 

 sea-shore. Dr. Baird observes, " They live among the fuci 

 and confervas, etc. which are to be found in such pools; and 

 the naturalist may especially find them in abundance in those 

 beautiful, clear, little round wells which are so frequently to 

 be met with, hollowed out of the rocks of the sea-shore, 



