1046 



CRUSTACEA. 



duplo geniculati et inflexi, 4-articulati, setis nudis longis. Styli caudales per- 

 breves, setis stricte appressis. 



2. Oculis sujperioribus et inferioribus instructi. 



G-. 4. Acartia, Dana.* — Frons rotundatus. Antennae lmas longae, rectiusculae, 



flexiles, setis quaquaversum insistentibus ornatae, dextrft maris non geniculate 



(?). Pedes postici feminoe, et maris (?) parvuli, uni-articulati, 2 setas divaricatas 



gerentes. Maxillipedes et pedes antici fere ac in PontelU. 

 G-. 5. Pontella {Pontia, Edwards). — Frons sive rotundatus sive triangulatus, 



rostro infra rigide furcatum. Oculi superiores sive coaliti sive late disjuncti. 



Antennas lmse longae, saepe oblique prorsus porrectae, antice regulariter setigeraa. 



Antennas posticae birameae, ranio anteriore setis quinque apice saepius confecto. 



Cephalothorax 4-7-articulatus. Maxillipedes pedibus anticis majores, recti, setis 



longis setulosis antice instructi. 



3. Oculis superioribus carentes. 



G-. 6. Catopia, Dana.f — Calano paulo affinis. Antennae lmae fere transversim 

 porrectae, regulariter setigerae. [In specie scrutata cephalothorax 4-articulatus, 

 styli caudales oblongi et divaricati, caputque quadratum.] 



The Calanidse, when not colourless, are usually tinged either with 

 reddish, bluish, or purplish shades. The red colour is often confined 

 to the internal parts near the mouth, and to the sides covering the 

 muscles of the legs. The blue colour is sometimes quite deep, and 

 occasionally it passes into a rich green. In several species, the back 

 has a silvery or pearly appearance. A few have the body, natatory 

 legs, and the antennae in part a rich black or brownish black. 



The species are widely distributed over all oceans, both in the 

 tropics, and far beyond, north and south. A hand-net of gauze 

 thrown at any time, but especially at night, or before daylight in the 

 morning, will almost invariably bring up some species. Calm weather 

 is the most favourable. At times, they occur in swarms that cover 

 square miles of ocean, giving the waters the bloody tint so often 



* Pontia, Edwards, Ann. des Sci. Nat., 1828, xiii. 296, and Crust., iii. 417; Ponttlla, 

 Dana, Am. J. Sci. [2], i. 228, and Proc. Amer. Acad. Sci., 1849, ii. 26. The genera 

 Anomalocera, Templeton, Trans. Ent. Soc, ii. 35, 1837, and Baird, Brit. Entomost., p. 

 229 ; and Irenceus, Goodsir, Jameson's Jour., 1843, xxxv. 337, are here included, as 

 they differ in no essential point from Pontia of Edwards. 



t Proc. Amer. Acad. Sci., 1849, ii. 25. 



