CRUSTACEANS 



larger ; striated circularly on exterior and upper margin, and spotted 

 with small black spots ; the anterior portion of the shell is of a red hue, 

 with a large, irregular-shaped, dark band running across the centre of 

 the shell, and occupying about half its extent. The beak is extremely 

 long, and at times appears to lie close to the body.' ] Eurycercus lamel- 

 latus (O. F. Miiller) is reported from Woking by the Quekett Club. 2 

 This is a large olive-coloured species, with the terminal part or post- 

 abdomen very broad and lamellar, characters to which the two technical 

 names allude. Dr. Baird says, 'The motion of this insect is peculiar; it 

 generally lives at the bottom of the vessel in which it is kept, and when 

 disturbed it bounds up by rapid short motions in a curved sort of line, 

 and then returns in the same manner to the place from where it rose. 

 It is very heavy and slothful compared with the other genera, and I have 

 frequently turned it over two or three times before it has moved.' 8 In 

 speaking of it as an insect Dr. Baird is here relapsing into the language 

 of an earlier classification, when crabs and crayfish were all included in 

 a heterogeneous mass of 'insects without wings.' A merciful dispensa- 

 tion has now relieved the over-burdened entomologist from regarding 

 anything as an insect that has more than one pair of antennas and more 

 than three pairs of legs. Camptocercus macrourus (O. F. Miiller) by its 

 generic name alludes to the flexibility of its tail, and by its specific name 

 to the length of it, the post-abdomen being 'very long, slender and 

 extremely flexible,' so that 'the animal can twist it completely round in 

 a circle, and then unbending it, thrust it far out beyond the shell.' * It 

 is reported by Baird from a ditch near Richmond, but whether he has 

 given it its right specific name is a little doubtful, Mr. Scourfield prefer- 

 ring to call it C. rectirosfris, Schodler. Also from a 'ditch near Rich- 

 mond' comes Acroperus harpce^ Baird. The generic name, signifying 

 pointed extremity, refers to the form of the shell, which is described as 

 4 somewhat harp-shaped, terminating inferiorly on anterior margin, in 

 a more or less blunt point, projecting forwards,' while the specific name 

 alludes to the sculpture of the surface, which is 'strongly striated, or 

 rather ribbed, longitudinally and somewhat obliquely, giving the shell, 

 which is quite transparent, a good deal of resemblance to a harp.' s 

 Alona quadrangularis (O. F. Miiller) is reported by Baird from the 

 same prolific source, a 'ditch near Richmond," and by the Quekett Club 

 from Walton. 7 A. ovafa, Baird, is reported by the same club from 

 Richmond Park. 8 A 'ditch near Richmond' further supplied Baird 

 with Peracantha truncata (O. F. Miiller), the genus instituted by Dr. 

 Baird for this species owing its name to the strong hooked spines with 

 which both extremities of the shell are beset. 9 



In the second section of the Cladocera the carapace is small, and 

 makes no pretence of sheltering the feet. Like the first section it is 



1 British Entomoitraea, Ray Soc. pp. 127, 128 (1850). 



* Q. M. C. ser. 2, vol. ii. p. 34. s British Entomostraca, p. 125. 



* Loc. fit. pp. 128, 129. 6 Lx. at. pp. 129, 130. 



8 Loc. cit. p. 132. i Q. M. C. ser. 2, vol. iii. p. 296. 



8 Loc. cit. ser. 2, vol. ii. p. 191. M British Entomostraca, p. 137. 



195 



