ME. E. J. MIEES ON THE IDOTEIDiE. 59 



stinctly bilobated at its apex. Thoracic segments nearly smooth 

 above, the first shortest, with its anterior margin deeply exca- 

 vated and the broadly-rounded antero-lateral lobes reaching to 

 the eyes ; postero-lateral angles of all the segments subacute. 

 Postabdomen strongly carinated in the middle line ; the keel 

 reaching quite to the posterior margin, uniarticulate, with three 

 very distinct lateral fissures (indicative of coalescent segments), 

 with the sides sliglitly convergent to the distal extremity, which 

 rounds off" to a small median cusp or point. Antennules not 

 reaching to the distal end of the antepenultimate joint of the 

 antennae, wliich do not usually exceed half the body in length ; 

 peduncle w^th the last two joints subequal and but little longer 

 than the preceding ; flagellum shorter than the peduncle, and 4- 

 to 6-jointed. The epimera of the three posterior thoracic seg- 

 ments only are visible in a dorsal view, and in these they are rather 

 broad, with the postero-lateral angles not acute, and are not pro- 

 longed beyond the posterior margin of the segments. Legs 

 very slender, almost filiform. Distal plate of the opercular 

 valves almost triangulate, with the apex subacute. The colour 

 (according to M. Lucas) is deep green ; all the thoracic segments 

 with their posterior and lateral margins margined with yellow ; 

 antennae yellowish ; antennules greenish yellow. Length -| inch 

 (21 millim.), breadth nearly I inch (6 millim.). 



I. carinata does not, so far as I am aware, extend beyond the 

 shores of the Mediterranean. 



The description is taken from specimens in the Paris collection 

 from Algeria (Lucas), one of which has been retained for the 

 British Museum, but the colour and measurements are from 

 M. Lucas's work. 



This species is very distinct from most of the genus, and in 

 several points approaches certain species of the genus Edotia, 

 from whicli it is distinguished by the distinct epimera of the 

 posterior thoracic segments and subparallel sides of the body. 

 There is no distinct oblique line on the basal plates of the 

 operculum. 



M. Lucas mentions the occurrence of this species at Bona and 

 Oran. 



Idotea acuminata. 



Stenosoma acuminatum, Leach, Edlnb. Encyl. vii. p. 4.33; id. Trans. 

 Linn, Soc. xi. p. 366 (181.5), 



