^K^-C^jps 



66 MR. E. J. MIEES ON THE IDOTEIDiE. 



The species of this section of tiie genus may be distinguished 

 as follows : — 



a. Terminal segment emarginate at its distal end. 

 Head with a median notch in its anterior margin ; terminal 

 plates of the valves o£ the operculum triangulate, acute at apex. 



1. JE. Mcuspida (Owen). 

 Head with the anterior margin entire ; terminal plates of the 



valves of the operculum four-sided, truncated at apex. 



2. :E. Urtipes (M.-Edw.). 



b. Terminal segment not emarginate at its distal end. 

 Head with its anterior margin notched ; terminal plates of the 

 opercular valves triangulate. 3. E. nodulosa (Kroyer). 



Idotea bicuspida, Owen, Crust, in Zool. Capt. Beechey's Voyage, p. 92, 



pi. xxvii. fig. 6 (1839) ; Streets ^' Kingsley, Proc. Essex Instit. ix. 



p. 108 (1877); Miers, Crustaceain Markham's Polar Reconnaissance 



p. 342 (1881). fiji„...juLwi. 



- Idotoa consolidata, Stimpson, Pr. Cal. Acad. Nat. Sci. i. p. 89 ; id. 



Boston Journ. Nat. Hist. vi. p. 503 (1853). 



Idotea marmorata, Packard, Mem. Boston Soc. Nat. Hist. i. (pt. 2) 



p. 296, pi. viii. fig. 6 (1867) ; Whiteaves, Canad. Nat. p. 262 (1875). 



? Idotea rugulosa, Buchholz, Cr. in Zweite deutsche Nordpolarf, ii. 



p. 285, note (1874). 

 Idotea pulchra, hockington, Pr. Cal. Acad. Sci. vii. (pt, i.)p. 45 (1877). 

 Synidotea bicuspida, Harger, Pr. U.S. Nat. Mus. ii. p. 160 (1879) ; id. 



Isopodain Rep. U.S. Fish Commission, pt. vi. p. 352 (1880). 

 Synidotea incisa, G. 0. Sars, Arch. f. Math, og Naturvidenskab. iv. 



p. 433 (1880). 

 Body ovate ; in the largest examples rather depressed. Head 

 transverse ; anterior margin nearly straight, with a small median 

 notch ; its antero -lateral angles prominent and nearly right 

 angles ; its upper surface very uneven, the inequalities defined by 

 strongly marked depressions. Thoracic segments short, of nearly 

 equal length in the middle line, where they are marked above 

 with two short transverse raised lines, and rugose on the sides 

 midway between the median line and lateral margins ; first three 

 or four segments with the antero-lateral and postero-lateral angles 

 broadly rounded ; the following segments with the postero-lateral 

 angles nearly right angles. Postabdomen in the adult about 

 equalling the four posterior thoracic segments in length, and 





