CRUSTACEANS 



as correct. Further records of these innocent and interesting animals, 

 which from their pellucid appearance may be supposed to live on water 

 as well as living in it, are much to be desired. 



In regard to woodlice it may be observed that winter is an un- 

 favourable season for collecting them, as they then show little or no 

 activity and are more than ever withdrawn from view ; nor should it 

 be supposed that only the species which have been here mentioned are 

 likely to be found. Several others might be named as almost equally 

 certain to occur, but they may be allowed to bide their time till con- 

 jecture has been replaced by observation. 



On turning to the Entomostraca we are confronted by possibilities 

 indefinitely larger. If inductive philosophy can in anything be trusted, 

 it will entitle us to affirm with supreme confidence that the waters ot 

 Worcestershire will yield Chydorus sphcericus and Daphnia pukx, for ex- 

 ample, among the Cladocera ; Cyclocypris serena among the Ostracoda ; 

 Cyclops viridis among the Copepoda. Mr. J. D. Scourfield, writing in 

 1897, says of the Entomostraca, 'The freshwater forms hitherto re- 

 corded may be estimated at 600, distributed as follows : Phyllopoda, 

 100; Cladocera, 200; Branchiura, 20; Ostracoda, 120; and Cope- 

 poda, 160. Of these we have in the British Isles, as far as yet known, 

 only about 190, namely Phyllopoda, 2 ; Cladocera, 75 ; Branchiura, i ; 

 Ostracoda, 58 ; and Copepoda, 54.' Of the three largely represented 

 groups several species have a more or less ubiquitous distribution. Of 

 the two phyllopods Apus cancriformis seems to be at present either very 

 rare in England or very seldom observed, whereas Chirocephalus diaphanus, 

 after passing out of sight for a time, is now regaining notice. A third 

 phyllopod, Artemia salina, was at one time well known as English, its 

 habitat at Lymington in Hampshire being repeatedly mentioned in 

 books concerned with Entomostraca. But it is no longer known at that 

 locality, and when two or three years ago I made enquiries about it 

 through a friend at Droitwich, this interesting brine shrimp was equally 

 unknown there. The manager of the salt works however obligingly 

 sent me some small beetles aHve in salt, in which he said they had 

 flourished for some weeks, having no other visible means of subsistence. 

 It will be remembered that Dr. Baird in his account of the brine 

 shrimps remarks that ' Their enemies, in such a fluid as the Artemia 

 inhabits, are not numerous ; but their chief foe is a small beetle allied 

 to the Dytiscus, which Mr. Joly observed at Montpellier, and proposes 

 to name Hydroporus salinus. When it meets an Artemia it darts at it 

 and bites it ; it then retires for a short time, but returns to the attack 

 again and again, till it succeeds, by numerous bites, in killing the poor 

 creature, and devouring it with astonishing avidity.' ' Between the 

 beetle and the shrimp our sympathy may be divided, for a diet exclu- 

 sively of salt must have a peculiar monotony, to relieve which we may 

 be sure that man himself would never hesitate to kill a crustacean. If 

 the Droitwich insects be the same as those observed at Montpellier, there 



* Baird, British Entomosh-aca, p. 60, Ray Soc. (1850). 

 ^ 129 K 



