Mr. C. Chilton on a new Species o/" Idotea. 123 



XII. — On a new Species o/" Idotea. 

 By Charles Chilton, M.A. (New Zealand). 



[Plate V. A. figs. 1-3.] 



In the ' New Zealand Journal of Science,' vol. i. p. 332, 

 Mr. G. M. Thomson gives a complete list of the New-Zealand 

 species of Idoteidae, altering some of the names by which the 

 species were previously known, in accordance with Mr. Miers's 

 elaborate revision of the family*. Of the seven species men- 

 tioned in this note I have only seen two — Idotea ungulata. 

 Pallas (previously known as /. affinis), and Idotea elongata. 

 White. Both of these are fairly common in Lyttelton Har- 

 bour, and I have also specimens of Idotea elongata from 

 Akaroa, collected by Mr. R. M. Laing. My specimens of 

 Idotea ungulata were all taken on green seaweed, which they 

 closely resemble in colour ; while Idotea elongata I have found 

 only on brown seaweed, and it is itself of the same colour. In 

 a note published in the ' New Zealand Journal of Science,' 

 vol. i. p. 517, I recorded the fact that in the mature female 

 of Idotea elongata the thorax with the brood-pouch is expanded 

 and attains its greatest breadth in the third segment, which is 

 twice as broad as long ; I find, however, that this had been 

 previously observed by Mr. Miers f. 



I am now able to add to the list another species of Idotea, 

 which appears to be new. It comes under Mr. Miers's sec- 

 tion ii. a* [see I. c. p. 25], but is quite distinct from the species 

 he mentions under that section. It was taken at Sumner, 

 Canterbury, N. Z., on the under surface of a boulder, which 

 was at the time not covered with water, since it was low tide. 

 I have only the one specimen. I append a detailed description. 



Idotea f estiva, sp. no v. (PI. V. A. fig. 1.) 



Body not very convex, oblong oval, length about two and 

 a half times the greatest breadth. Head transverse, produced 

 upwards and forwards into a rounded prominence divided into 

 two lobes by a median depression, which is continued nearly 

 to the posterior margin ; remainder of the head variously 

 sculptured and with two raised ridges towards the lateral 

 borders. First five segments of the thorax of nearly equal 

 length, sixth and seventh shorter, seventh shorter than the 



* 'Journal of the Limiean Society,' vol. xvi. p. 1. 

 f Loc. cit. p. 55. 



