40 NEW-YORK FAUNA — CRUSTACEA. 



ORDER IV. LCEMIPODA. 



Head united to the first segment of the thorax. Eyes sessile. Branchial apparatus, or what 

 is presumed to be such, vesicular, and from four to twelve in number. Abdomen rudimen- 

 tary, having the form of a small tubercle, without distinct appendices. Marine. 



GENUS CYAMUS. Latreille. 



Body broad, depressed. Head short, truncate. Antennae four, approximated at their bases; 

 the two upper setaceous, longest. Feet twelve, of which eight are perfect, and the others 

 in the form of slender jointed appendices under the second and third segments of the body. 

 Two compound sessile eyes on the anterior and lateral portions of the head, and two others, 

 smooth, on the vertex. Parasitic. 



Cyamus ceti. 

 plate vi. fig. 14. 



Oniscus ceti. Lin. Syst. Nat. 3011. 



Cyamus id. Latreille, Gen. Crustac. Vol. 1, p. 60. 



C. id. Gould, Invertebrata of Mass. p. 335. 



Description. Head small, conical. Body depressed, oval-orbicular, composed of six seg- 

 ments somewhat distant from each other ; the last with a small terminal appendix. Antennae 

 of four articulations, the last of which is small and conic ; the upper as long as the head and 

 first segment. Mouth with the lower lip formed by two jointed unguiculated palpi. First 

 pair of feet short, of six articulations terminating in a hand with movable curved claw. 

 Second and third pairs replaced by slender appendices, at the bases of which are the 

 branchial vesicles. Fourth, fifth and sixth pairs complete ; the fourth largest, the others suc- 

 cessively smaller, all robust ; the first joint large and rounded, the penultimate oval, the last 

 pointed and forming with the preceding a monodactyle claw. Color, yellowish white. 



Length, 0-5-0-8. 



This species, which is known under the name of Whale Louse, is usually found attached 

 to the bodies of whales along our coast, and occasionally on tunnies and other large marine 

 animals. It varies much in form according to its degree of development, and this has given 

 rise to several nominal species, which have not yet been sufficiently examined. 



(EXTRA-LIMITAL.) 



C. abbrevialus. (Say, Jour. Ac. Vol. 1, p. 393.) Hands of the second pair with the palm two-toothed 

 and much larger than the others; one tooth near the base, and the other near the tip. Branchial 

 vesicles half as long as the feet. Length, • 1. Hab. Bal. 



