lUOTHEA NEGLECTA WITHIN THE CLYDE AREA. 43 



The six species belonging to this family recorded by Dr. Thomas 

 Scott, F.L.S., from the Firth of Clyde in 1901 ave-.—Idothea 

 baltica (Pallas) j /. pelagica, Leach; /. emarginata (Fabr.); 

 /. linearis (Pennant) ; Zmohiana prismatica, Risso ; and Steno- 

 soma acuminata (Leach).* 



During some recent dredging cruises on the steam yacht 

 "Mermaid," of the Millport Marine Biological Association, I 

 collected at several localities quite a large number of specimens, 

 representing several of the species of this family. Upon exami- 

 nation, I found a number of these specimens to agree with the 

 description and figures, by Professor G. O. Sars, of the two 

 species, Idothea neglecta, G. O. Sars, and I. viridis (Slabber). t 



These species have not yet apparently been recorded from the 

 Firth of Clyde, nor probably from the British seas. 



Idothea neglecta in some respects resembles not only 

 /. emarginata, but also /. baltica, and doubtless has been passed 

 over by former observers as belonging to the latter species. 

 Sars obsei^res, "there cannot be any doubt that this very 

 common form must have been observed by several authors. It 

 has not yet been recognised as a distinct species, but has either 

 been regarded as merely a variety of /. baltica, or as /. pelagica 

 of Leach." t There is little doubt, however, as to the distinct- 

 ness of the species. 



While it agrees with /. baltica in having the coxal plates 

 contiguous, which form, as in that species, a broad marginal area, 

 it differs principally in the structure of the stylets of the second 

 pair of pleopoda of the male, which are much shorter and do not 

 reach much beyond the middle of the inner plate, whereas in 

 /. baltiea they reach almost to the end of the inner plate, and in 

 the terminal segment of the metasome, which is slightly narrowed 

 distally and terminates in a blunt point, the lateral corners being 

 rounded off, whilst in /. baltica it has a distinctly tridentate 

 form. 



The largest male specimen in my collection measures 35 mille- 

 metres. 



* Hand Book of Natural History, British Assoc. Mg., Glasgow, 19U1. 

 + Crustacea of Norway, Vol. II., Isopoda, pp. 83-85, pis. 34-35. 

 t Op. cit. p. 84. 



