H06 CRUSTACEA. 



Plate 78, fig. 10 a, animal, enlarged ; b, extremity of antenna. 



Collected in the Pacific, near El Gran Cocal, latitude 5° 30' south, 

 longitude 175° east, March 25, 1841. 



Length, one-sixteenth of an inch. Colour, bluish, with a reddish 

 tint in the head and abdomen. The species is near the Calani in 

 habit. The body is slender, narrower anteriorly. The eyes are ap- 

 proximate, but were not quite clearly seen. The male right antenna 

 differs but little from the female, as the joints are all distinct, and a 

 few only are a little enlarged, without affecting much the terete cha- 

 racter of the organ. These antennae are nearly in the same straight 

 line, after the first curving at base ; each inclines a little back of an 

 exact line. The second joint is oblong, full twice as long as broad; 

 the apical is a little longer than the penult. After the geniculating 

 articulation there are five joints, the first and second hardly coalescent 

 and very nearly straight, the last three but little longer than the other 

 two. The setae are all short, those towards the base about twice as 

 long as the diameter of the joints, and much crowded. The second 

 pair of antennae is rather small; one branch consists of two nearly 

 equal joints, and has three setae at apex, like the Calani, and several 

 on the back surface of the first joint. The setae are rather small. The 

 other branch is much the shorter. 



Cyclopsina calanina, Dana, Proc. Amer. Acad. Sci., ii. 25. 



Hemicalantjs TENUICORNIS. 



Maris : — From triangulatus. CepTxalothorax postici fere obtusus, 1-arti- 

 culatus, capite discrete, segmentis posticis ceqtiis. Antennce atiticce cor- 

 pore vix longiores, apicibus f route vix anterior ibvbs, tenuissimm, rectius- 

 culce, setis brevibus, anticis apicalibus fere articuli longitudine, posticd 

 penultimd paulo longiore. Antenna maris dextra parce incrassata, 

 articulis nullis coalitis. Abdomen ?y-articulatum. Styli caridales 

 elongati, divaricati. 



Male : — Front triangular. Cephalothorax behind nearly obtuse, seven- 

 jointed, head separate, four posterior segments subequal. Anterior 



