94 Dr. W. Baird on British Entomosiraca. 



t. 10. f. 5, 6.— Monoculus trigonellus, Linn. Gmel. 3008. no. 63 ; 



Manuel, Encyc. Mrth. vii. 733. no. 63. t. 268. f. 24, 25.— Fabri- 



cius, Ent. Syst. p. 498. — Lynceus trigonellus, LatreiUe, Hist. gen. 



et part, des Crust, p. 205 ; Lamarck, An. sans Vert. 123. no. 2 ; 



Baird, Trans. Berw. Nat. CM, p. 100 ; M. Edwards, Hist, des 



Crust, iii. p. 387. 



Shell somewhat triangular-shaped and transparent ; gib- 

 bous on upper portion on anterior edge for about a third of 

 its length, the other two-thirds being truncated, or as it were 

 cut obliquely with a straight sharp edge, and ciliated. Pos- 

 terior margin gibbous also, and sinuated near lower extremity, 

 which terminates in a square point. Beak long, curved and 

 sharp-pointed. First pair of feet very large ; the pediform 

 organ of Miiller being the first pair of feet. Rami short and 

 slender. The anterior branch has four setae, one from first 

 articulation, one from second, and two from last. Posterior 

 branch has three setas, all springing from last joint. Tail 

 gibbous for latter half, and serrated. Intestine convoluted, 

 having one turn and nearly a half. Eye areolar. 



Hab. Pond near Copenhagen fields ; at Osterly Park, Nor- 

 wood Green and Southall; '^pond at Foulden and at Yet- 

 ho\m:'— Trans. Berw. Nat. Club. 



2nd Sp. Plevroxiis hamatus. PI. III. f. 14. 

 Syn. Lynceus hamatus, i?fl/rrf, Trans. Berw. Nat. Club, p. 100. t. 2.f. 18. 



" Shell truncated anteriorly and ciliated ; upper part gib- 

 bous ; tail not serrated, gibbous, terminated bytwosetee*; 

 two upper feet large, and each furnished at extremity with a 

 strong hook or claw turned upwards ; antennasf of three setag 

 each. x\pproaches Lync. trigonellus, but differs from it in the 

 beak being blunted and stronger, in the tail not being serrated, 

 and in the upper feet having the strong hooksj. 



Hab. Yetholm Loch, Roxburghshire." — Trans. Berw. Nat. 

 Club. 



1 first found this species in the autumn of 1835 in Yetholm 

 Loch, Roxburghshire, and afterwards in a pool near Yetholm 

 Bridge, but have not since met with it. The intestine is 

 curved, and the shell extremely transparent. 



8th Subgenus. Peracantha§. " Oval-shaped ; the lower 

 extremity of shell slightly curved backwards, and, as well as 

 upper extremity of anterior margin, beset with strong hooked 

 spines.'' 



1st Sp. Peracantha truncata. Pl. IIL f. 15. 



Syn. Lynceus truncatus, Mull. Entom. 75. t. 11. f. 4 to 6. — Monoc. 



* Claws ov hooks. 



I Rami. + It is only about half the size of //v^owcZ/j/s, 



^ From TTsjaj extremity, and oiKuuSx spine. 



