DIAPTOMUS. 219 



Genus I DIAPTOMUS. * 



MONOCULUS, LitttHKMs, Fabwiits, Jurine, fyc. 

 CYCLOPS, MiUler, Desmarcst, Manuel, $-c. 



DIAPTOMCS, /. 0. Westwood, Partingtou's Cyclopsed. Nat. Hist., 

 art. Cyclops, 183G ; Entomologist's Text-Book, 183 8. 

 OMETHIA. Templeton, Trans. Ent. Soc., ii, 118, 1838. 

 CYCLOPSINA,! M. Edtcards, 1840. 



Pliilifpi, Wiegm. and Erichs. Archiv, 1843. 

 Baird, Zoologist, i, 56 ; Trans. Berw. Nat. Club, ii,154. 

 Dana, 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. DJAPTOMUS CASTOR. Tab. XXVI, figs. 1, 2, 2 a-j. 



MONOCULUS CASTOK, Jurine, Hist. Nat. Monoc., 50-73, t. 4-6, 1820. 

 CYCLOPS CASTOK, Desmarest, Cons, gen., 363, t. 53, f. 5, 1825. 



Baird, Mag. Zool. and Bot., 324, t. 10, f. 1-8. 

 CYCLOPS OEBULEUS, Matter, Zool. Dan. Prod., No. 2411, 1776 ; 



Entomost., 102, t. 15, f. 1-9. 

 Latreille, Hist. Nat. Crust., iv, 265. 

 Bosc, Man. Hist. Nat. Crust., ii, 257. 



MONOCULUS C^RULEUS, Fubricius, System. Eutomolog., 295. 



Manuel, Enc. meth., t. 264, f. 1-9. 

 Gmel'm, Linn. Syst. Nat., 2997, No. 12, 

 edit. 13th. 



* From f t, through ; and nrra^ai, to fly. 



+ Though the genus Cyclopsinn 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. 



