226 CRUSTACEA. 



NATJPREDIA, Lat. 



But ten feet, all in one continuous series ; the base of the second 

 and two following pairs provided with a vesicular body *. 



CAPRELLA, Lam. 



Ten feet also, but in an inlerrupted series, commencing with the 

 second segment, exclusive of the head ; both this segment and the 

 following have two vesicular bodies, and are totally deprived of 

 feetf. 



The other OVALIA, Lat, Lsemodipoda have an oval body with 

 transversal segments. The stem of the antennae appears to be inar- 

 ticulated, and the feet are short but slightly elongated; those of the 

 second and third segments are imperfect and terminated by a long 

 cylindrical joint without a hook ; their base is provided with an 

 elongated vesicular body. They form the subgenus. 



CYAMUS, Lat. LARUNDA, Leach. 



I have seen three species, all of which live on the Cetacea ; 

 the most common, Oniscus ceti, L.; Pall., Spicil. Zool. Fascic. 

 IX, iv, 14; Squilledela Baleine, De Geer,Ins., VII, vi, 6; Pyc- 

 nogonum ceti, Fab. ; Savig., Mem. sur les anim. sans verteb. 

 Fascic., I, v, 1, is also found on the Mackerel : it is called by 

 fishermen Pou de Baleine. A second very analogous species 

 was brought to France by the late Delalande from the Cape of 

 Good Hope. The third, which is much smaller, establishes 

 itself on the Cetacea of the Indian Ocean. 



ORDER V. 



ISOPODA j. 



The Isopoda approach the Laemodipoda by the palpi of the man- 

 dibles being absent, but are removed from them in several other re- 



* A subgenus founded on a species from the coast of France, which appears to me 

 undescribed. 



f* The Squilla lobata, Miill., Zool. Dan., LVI, 4, 6 ; his Gammarus quadrilobatus, 

 Ib., CXIV, 12; the Oniscus scolopendroides, Pall, Spic. Zool. Fascic., IX, iv, 15, are 

 Caprellae, but their specific differences are not well characterized. We had referred 

 the Cancer linearis, L., to the first, which, now appears doubtful. His Cancer 

 filiformis is probably a Caprella ; the Cancer phasma, Montag., Trans. Lin. 

 Soc., VII, vi, 2, is a congener. His figure is copied Eucyc. Method., Atl. d'Hist. 

 Nat. CCCXXXVT, 37. For details concerning this order and genus, see the Nouv. 

 Diet. d'Hist. Nat., Ed. II, and the work of Desmarest on the Crustacea. 



J The Polygouata, Fab., with the exception of the genus Monoculus. 



Messrs. Audouin and Edwards Ann. des Sc. Nat., About 1827, p. 379, 381 

 treve published some interesting observations on the circulation of the Isopoda, and 



