CRUSTACEANS 



So lately as ten or twelve years ago the Crustacea of this county were 

 still suffering from a kind of conspiracy of silence. A few Entomostraca, 

 noted as occurring in pools and ditches round London, might be presumed 

 to inhabit this part as well as others of that great circumference. One 

 important species is recorded by Baird, on the authority of E. Doubleday, 

 Esq., as having been taken ' near Epping.' l On the not improbable 

 assumption that this was found within the borders of the county, Essex 

 may include in its fauna the beautiful non-crustaceous crustacean, Cbiro- 

 cephalus diaphanus, Prevost. This is a creature that collectors may accuse 

 of caprice. Its appearances are fitful. The secret lies in its adaptation 

 to shallow patches of water, liable to complete desiccation. Though it 

 cannot itself survive the vanishing of its native pool, its eggs will rest 

 contentedly in an expanse of dried mud or meadow, till some miniature 

 deluge, instead of destroying them, restores them to a watery world. In 

 this they speedily hatch, pass through their larval stages, and in the adult 

 form are distinguished by their glassy length, the constant movement of 

 their leaf-like limbs, and by the negative character of having no carapace. 

 The graceful slenderness of this species is in strange contrast to the 

 clumsy, sullen-looking figure of the hard and hairy-coated Dromia, a rare 

 crab, and the only one that Adam White in his Popular History of British 

 Crustacea^ assigns to Essex. Unfortunately White seems to have been 

 less trustworthy as a geographer than as a carcinologist, for he says that the 

 Dromia vu/garis was ' first recorded as British by Dr. Gray, who obtained 

 a specimen in Billingsgate market, amongst oysters from Whitstable in 

 Essex, in 1825.'* It is possible that, using a very small map, he found 

 the name of Whitstable stretching all across the mouth of the Thames, 

 and so fell into the confusion of transferring the place from the southern 

 bank of the river to the northern. 



For vagueness and inadequacy in the past science has lately been 

 making ample amends, and when a thorough investigation of its Mala- 

 costraca and salt water Entomostraca has been completed, the county 

 may find that its marine Crustacea are as diversified and interesting as 

 those of its inland waters have been already proved to be. 



Of the Brachyura or short-tailed crabs, Mr. Edward Lovett has 

 recently published the following records. After mentioning that ' the 

 spider crabs of the genera Stenorhynchus and Inachus are very delicate in 

 structure, and occur in deep water in the western parts of the Channel,' 

 he continues, ' Stenorhynchus rostratus is common in the Thames estuary. 

 A more robust form Hyas araneus (and its near relative H. coarctatus] are 



1 British Entomostraca, Ray Soc. p. 54 (1850). 2 Popular Hist. Brit. Crust, p. 68 (1857). 



204 



