356 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



This species was originally described from Great Egg Harbor, New 

 Jersey, where Say found it in company with Idotea irrorata. It is not 

 uncommon along the shores of Long Island Sound! and as far east as 

 Vineyard Sound, Mass. ! but has not yet been found north of Cape 

 Cod. It is usually found in tide-pools or among eel-grass and alga3, 

 and has been taken from a depth of 7 fathoms. 



Specimens examined. 



Erichsonia attenuata Harger. 



Erichsonia attenuata Harger, This Report, part i, p. 570 (276), pi. vi, fig. 27, 



1874 ; Proc. U. S. Nat. Mus., 1879, vol. ii, p. 160, 1879. 

 Verrill, This Report, part i, p. 370 (76), 1874. 



PLATES VI and VII, FIGS. 36 and 37. 



This species is at once distinguished from the preceding by its slender 

 form and regular outline ; the clavate antennal flagellum distinguishes it 

 from other Isopoda. 



The body is smooth throughout and about six times as long as broad, 

 without prominent irregularities and narrowly linear in outline. The 

 eyes are small and black. The antennulae (pi. VII, fig. 37 a) are short, 

 slightly surpassing the second antennal segment. The antennae (pi. VII, 

 fig. 37 b) are stout and smoother than in the preceding species. The 

 external lamella of the maxillipeds (pi. VII, fig. 37 c, I) is oval and 

 regularly rounded at the tip. 



The thoracic segments increase in size to the third, which is equal 

 to the fourth, and the last three are of a gradually decreasing size. The 

 epimera are nowhere conspicuous, but may usually be seen from above, 

 especially in the posterior segments. 



The pleon presents only slight traces of a lateral tooth near its base 

 wid is but little dilated toward the tip. The operculum (pi. VII, fig. 

 11 d) is longer than in the preceding species, the basal plate is more 

 than three times as long as broad, the terminal plate elongated trian- 

 gular and obtuse. The male stylet on the second pair of pleopods 

 (pi. VII, fig. 37 e, s) is nearly straight, hardly surpasses the cilia, and 

 is minutely denticulated near the acute apex. 



