ME. E. J. MTEES ON THE IDOTEIDiE. 55 



rouudod postero-lateral lobes, and a moderately deep rounded notch 

 at its distal end. Eyes small. Autenniiles scarcely reachino- to 

 the distal end of the antepenultimate joint of the antenna?, which 

 liave a short peduncle, the last two joints of which are subequal 

 and each but little longer than the antepenultimate joint ; flageHum 

 18-22-jointed : when retracted the antennae do not reach beyond 

 the posterior margin of the fourth thoracic segment. Legs very 

 slender. Epimera scarcely visible in a dorsal view ; in a lateral 

 view they are very narrow, linear, and the last pair only reach to 

 the postero-lateral angles of the segment with which they are 

 articulated. Terminal plates of the opercular valves somewhat 

 longer than broad, four-sided, with the distal ends truncated or 

 very slightly emarginated. Length of a full-sized male about 

 2 inches (SOmillim.), breadth about jinch (7millim.). 



Specimens, apparently males, are in the Museum collection 

 from the Auckland Islands (Antarctic Esped.), preserved dry; 

 and a good series of both sexes, preserved in spirit, from the 

 Ealkland Islands (Antarctic Exped.). 



When I drew up the original description I had not observed 

 that the Ealkland-Island examples were of the same species, and 

 basing my diagnosis on the dried examples only, I fell into one 

 or two inaccuracies : thus the head is not generally coalescent 

 with the first thoracic segment, and the thoracic segments not 

 always longer than broad. In females with fully-developed brood- 

 pouches, the second to fourth thoracic segments appear laterally 

 dilated in a dorsal view. 



In the Paris collection there are six specimens from Auckland, 



Idotea Peeonii. (Plate II. figs. 6 & 7.) 



Idotea Peronii, M.-Edw. Hist. Nat. Cr. iii, p. 133 (1840). 

 Idotea distincta, Guerin-Meneville, Icon. Rhgne Anini., Cr. p. 33 (1829- 

 44). 



Body narrow-oblong rather than oval, not carinated, nearly 

 smooth. Head emarginate anteriorly, the middle of the notch 

 straight ; the antero-lateral angles rather prominent and rounded. 

 First thoracic segment with the antero-lateral lobes rather broad, 

 and not reaching nearly to the eyes. Postabdomen as long as 

 the four or fire posterior thoracic segments ; tei'minal segment 

 with two small sutures on each side near the base (indicative of 

 coalescent segments) and with subparallcl sides, distal end 

 usually broadly triangulate, and apex subacute. Eyes of mode- 



