44 NEW-YORK FAUNA — CRUSTACEA. 



This beautiful and active species is seen swimming with a rapid vibrating motion in clear 

 salt water, in recesses among the rocks. It appears to be most abundant in August and Sep- 

 tember. As far as we know at present of its geographical distribution, it is found from 

 Boston harbor to Cape May, but it probably extends along our whole coast. 



(EXTRALIMITAL.) 



S. filiformis. (Say, I.e. p. 424.) Body very much elongated, linear; segments distant, emarginatc 

 each side. Eyes very prominent. Antennas robust; outer more than half the length of the body ; 

 the last joint enlarged. Length, • 4. Egg harbor. 



GENUS ANTHURA. Leach. 



Body oblong-linear, vermiform. Tail furnished with foliaceous laminae on each side ; penul- 

 timate segment very short, the last much longer. Antennae short ; the intermediate oneg 

 rather shortest. Anterior feet with a movable nail. 



ANTHURA GRACILIS. 



PLATE IX. FIG. 34. 



Oniscus gracilis. Montagu, Tr. Lin. Soc. Vol.9, p. 366. 



Anthura id. Leach, Desm. Consid. Crustac6s, p. 291, pi. 46, fig. 13. 



A. id. Gould, Iuvertebrata of Mass. p. 338. 



Description. Body elongated. Feet subequal ; the second pair smallest ; the first pair 

 largest, robust, terminating in a small subcheliform hand. Two pair of foliaceous elongated 

 lamina? on each side of the last caudal segment, which is subtruncate behind. 



Length, 0"25. 



{EXTRALIMITAL.) 



Genus Sphjeroma, Latreille. Body oblong, convex, with subimbricated transverse segments, and 



contractile into a sphere. Antennas four, small ; the external slightly longest. Tail of two 



segments ; the last with a fin on each side, formed of two scales. Marine. 



S. quadridentata. (Say, I.e. p. 400.) Body oval, punctured. Tail with its last segment semioval ; 



the internal lateral lamella acute, entire ; the external one serrate on the outer edge with four teeth. 



Color, brownish ferruginous, often varied with white or rosaceous. Length, 0-45. Coast of 



Georgia and Florida. 



