IDOTEA EMARGINATA. 387 



OUR figures of this species are derived from Dr. Leach's 

 largest specimen, preserved in the British Museum (No. 

 1,000). It is very closely allied to I. tricuspidata, the 

 chief difference being that the central point of the ex- 

 tremity of the tail (of which a very slight trace may be 

 observed in certain individuals) does not extend so far 

 back as the prolonged lateral angles, and the epimeral 

 scales (coxae) of the six hind pairs of legs are widely 

 developed on the dorsal surface of the body, which is 

 covered with minute dark-coloured dots. 



The basal segments of the tail are also formed as 

 in /. tricuspidata, but the lower pair of antennae are 

 comparatively shorter. 



Various specimens, captured in different parts of the 

 British coast by Col. Montagu and Dr. Leach, are con- 

 tained in the British Museum. 



Mr. Robertson lias sent it to us from Cumbray, and 

 the Rev. A. M. Norman from the coasts of Durham and 

 Nor th um b e rlan d . 



It has also been taken at Port Patrick and Dundrum, 

 Ireland, by the late Mr. W. Thompson. Mr. W. P. 

 Cocks found this species among trawl refuse of fishing 

 boats, also in the stomach of fish at Falmouth. It is 

 common among weeds all round the coasts of Europe. 



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