42 NEW-YORK FAUNA CRUSTACEA. 



ORDER V. ISOPODA. 



Body more or less depressed, divided into segments varying in number from three to seven. 

 Head distinct from the first segment of the body. Mandibles without palpi. Mouth 

 with three pair of jaws. Feet ten to fourteen. Tail of one or more segments, supporting 

 the branchiae. Eyes sessile. 



GENUS IDOTEA. Fabricius. 



Body oblong-ovate. External antenna? moderately long, setaceous ; the peduncle with four 

 joints, and the extremity many-jointed: internal antenna? placed slightly above the outer, 

 small, filiform. Head subquadrate. Two sessile eyes. Tail large, of three segments, the 

 last without any terminal appendices, and covering the branchiae and the two lamina? which 

 protect them. Feet subequal. 



IDOTEA C<ECA. 



Idolea coeca. Say, Journ. Acad. Nat. Sciences, Vol. 1, p. 424. 

 /. id. Gould, Invertebrata of Mass. p. 337. 



Description. Body oblong-oval, broadest at the third or fourth segment, attenuated behind. 

 Head quadrate, depressed, with a deep fissure on the sides. Antenna? approximated at the 

 base. First segment of the tail short ; second somewhat trilobate ; last segment nearly or 

 quite half the length of the body, attenuated to an acute conic point, subcarinate above. 

 Three anterior pairs of feet robust, monodactyle ; the remainder simple, unarmed, and with 

 rigid hairs. Nails of the hind pairs rectilinear. Eyes inconspicuous. 



Color, whitish varied with brown dots, occasionally confluent into bands ; eyes milk white ; 

 head with a transverse black band. 



Length, 0-3-0-5. 



This little species occurs on all sandy shores from Massachusetts to Florida, where it forms 

 the little serpentine tracks noticed in the sand. The figure of the 7. tricuspis of Europe 

 (PI. 9, fig. 35), is introduced to illustrate the genus, as no opportunity has presented itself of 

 figuring the American species. 



