DIAPTOMUS. 
219 
Gems 1 — Diaptomus. * 
Monoculus, Linnaeus , Fabricius, Jurine , 8fc. 
Cyclops, Muller , Lesmarest, Manuel, Sfc. 
Diaptomus, J. 0. Westwood, Partington’s Cyclopsed. Nat. Hist., 
art. Cyclops, 1836 ; Entomologist’s Text-Book, 1838. 
Omethia, Templeton, Trans. Ent. Soc., ii, 118, 1838. 
Cyclopsina,! M. Fdwards, 1840. 
— Philippi, Wiegm. and Erichs. Arckiv, 1843. 
— Baird, Zoologist, i, 56 ; Trans. Berw. Nat. Club, ii, 154. 
— Lana, Proc. Amer. Acad. Sc., 1847. 
Character. — Head distinguishable from body, though 
firmly articulated with the first ring of thorax. Thorax 
and abdomen, each of five segments. Antennules com- 
posed of two branches. Foot- jaws not branched. Legs 
five pairs ; the first pair having one branch of three arti- 
culations, and the other of two; the three succeeding 
pairs having each a branch of three joints. External ovary 
large, single,, and lying across the abdomen. 
1 . Diaptomus Castor. Tab. XXVI, figs. 1 , 2, 2 a-j. 
Monoculus Castor, Jurine, Hist. Nat. Monoc., 50-73, t. 4-6, 1820. 
Cyclops Castor, Lesmarest, Cons, gen., 363, t. 53, f. 5, 1825. 
— Baird, Mag. Zool. and Bot., 324, t. 10, f. 1-8. 
Cyclops c^ruleus, Muller, Zool. Dan. Prod., No. 2411, 1776; 
Entomost., 102, t. 15, f. 1-9. 
— Latreille, Hist. Nat. Crust., iv, 265. 
— Bose, Man. Hist. Nat. Crust., ii, 257. 
Monoculus casruleus, Fabricius, System. Entomolog., 295. 
— Manuel, Enc. meth., t. 264, f. 1-9. 
— Gmelin, Linn. Syst. Nat., 2997, No. 12, 
edit. 13th. 
* Erom dia, through ; and nTrapai , to fly. 
f Though the genus Cyclopsina has been adopted from M. Edwards by 
Philippi, and heretofore by myself, yet as its founder includes other species 
belonging to the family in it which, as I have shown above (p. 204), cannot 
be received, and as Mr. Westwood, four years previous to the publication 
of M. Edwards’s work, distinctly defined the genus Diaptomus, I now, obeying 
the law of priority, assume his name ; and, indeed, while Mr. Westwood’s 
paper in which he founded the genus was still in MS. I had already indicated 
his name for it in the ‘Trans. Berw. Nat. Club’ for 1835. 
