Dr. W. Baird on British Entomostraca. 91 



4th Subgenus. Camptocercus*. "Ovoid-shaped. Tail 

 long, slender and extremely flexible, serrated." 



1st Sp. Camptocercus macrourus. PL III. fig. 5, 6. 

 Syn. Lynceus macrourus, Mull. Zool.Dan. Prod. 2397 ; Entom. t. 10. 



f. I to 3. — Monoculus macrourus, Linn. Gmel. 3008. no. 65 ; 



Manuel, Enc. M&h. vii. 733. no. 65. t. 268. f. 26, 27 ; Fabricius, 



Ent. Syst. ii. 499. — Lynceus macrourus, Latreille, Hist, des Crust. 



207 ; M. Edwards, Hist, des Crust, iii. 



Of an ovoid shape. Shell pellucid and whitish, finely stri- 

 ated or ribbed longitudinally ; slightly sinuated and ciliated 

 on anterior margin. Beak rounded and bluntish. Rami short. 

 Tail very long and slender, with thirteen well-marked serrae 

 or teeth on lower edge, and several smaller ones, terminating 

 in two long and slender claws ; setae short. This organ and 

 lower part of body is extremely flexible, and the animal can 

 twist it completely round in a circle, and then unbending it 

 thrust it far out beyond the shell. Eye small but areolar; 

 accompanying black spot nearly as large as the eye. First 

 pair of feet large. Intestine convoluted once and about a half. 

 Antennae rather long and slender, the terminating setae long 

 also. Anterior branch of rami has four long filaments and one 

 short one ; one long from second articulation, and three long 

 ones and one short from last. Posterior branch has only three 

 long filaments and one short from last joint. 



Hab. Ditch near Richmond, pond top of Brazil Mill-lane 

 near Isleworth, and at Highgate. 



5th Subgenus. AcROPERUsf. " Shell somewhat harp- 

 shaped, terminating inferiorly on anterior margin in a more 

 or less blunt point projecting forwards. Rami rather long." 



1st Sp. Acroperus harpa. PL III. fig. 7. 

 Syn. Lynceus harpse, Baird,Trans.Berw.Nat. Club, p. 100. t. 2. f. 17. 



Shell rounded posteriorly, sinuated rather deeply and ci- 

 liated anteriorly, and terminating in an obtuse point projecting 

 forwards ; strongly striated or rather ribbed longitudinally 

 and somewhat obliquely, giving the shell, which is quite trans- 

 parent, a good deal of resemblance to a harp. Beak rounded 

 and obtuse. Rami slender, and of considerable length, each 

 branch provided with three long setae from the extremity of last 

 articulation only. The rami and setae together extend almost 

 the length of the shell, reaching nearly to the inferior extre- 

 mity. Tail slender, not serrated on under edge, but marked 

 near the edge with a row of indentations, and terminating in 

 two claws, which are long and slender. Antennae of consi- 

 derable length, the terminating setae being much longer than 



* From Kxp'XTog flexible, and ks£kos a tail. 

 f From ocK^i pointed, and nieces the extremity. 



