IDOTEA LTNEARTS. 389 



Idotea diodon. LATREILLE, Nouv. Diet. d'Hist. Nat. xvi. p. 105. 



G-UERIN MEN. , Exp. Morce, p. 49. 



Idotea viridisstma. Risso, Crust, de Nice, p. 136, pi. 3, fig. 8. 

 Idotea kectica. LEACH, Edinb. Enc. vi. p. 404. 



Stenosoma hecticum. LEACH, Linn. Trans, vii. p. 433. 

 Oniscus unyulatus. PALLAS, Spic. Zool. 9, 62, tab. 4, f. 11 (antennis 



falsis ?) 



THIS large species is at once distinguished by its parallel 

 and sub-depressed form, and the very robust joints of the 

 peduncular portion of the lower antennae, which organs 

 are nearly as long as the whole body ; the flagellum ter- 

 minated by two very minute articuli (c. x.) ; the front 

 margin of the head is strongly sinuated, with the lateral 

 lobes elevated ; the upper surface of the whole animal 

 is uneven. The second, third, and fourth segments of 

 the body exhibit a small portion of the epimera-like 

 base of the legs at their anterior angles, whilst the fifth, 

 sixth, and seventh joints have the posterior angles cutoff, 

 and replaced by the same portion of the legs. The first 

 two segments of the tail are quite distinct, but the third 

 is only separated from the large terminal segment at the 

 sides, being completely soldered with it in the middle ; the 

 legs gradually but slightly increase in length, from the 

 first to the seventh pair, each being armed with a long 

 and strong simple hook-like finger. The tail occupies 

 one-third of the entire length of the animal. 



The operculum reaches to the posterior margin of the 

 caudal segment, and has the second joint narrower than 

 the first, and terminating in a rounded extremity. 



This species occurs in many parts of the British coast. 



We have received specimens from Cumbray from Mr. 

 Robertson; from Guernsey, Falmouth, and the coast of 

 Durham from the Rev. A. M. Norman ; and we have 

 dredged it in Bigbury Bay, near Plymouth, on which 

 coast it is by no means common. 



