AMPHIPODA AND ISOPODA OF THE FIRTH OF CLYDE. 49 



The male (Robertsoni) was dredged by the late 

 Dr. Jeffreys in the Shetlands. 



bathyporeia pelagica, Spence Bate. 



Bathyporeia pelagica, Spence Bate, Cat. Amphip. 

 Brit. Mus., p. 174, pi. xxxi., fig. 6. 



Thersites pelagica, Spence Bate, Rep. Brit. Assoc. 

 1855, p. 59. 



Habitat. — Taken off Callum's Bay, Bute, in 16 

 fathoms, bottom sandy mud; off Ardrossan in 20 

 fathoms, bottom stones and mud; and west of Tan, 

 Cumbrae, in 10 fathoms, bottom mud and stones. 

 It has also been taken in the Moray Firth by the 

 Rev. Geo. Gordon, in a considerable depth of water. 



Boeck and Norman doubt whether this is other 

 than B. pilosa, Lindstrom. It differs in some minor 

 particulars from B. pilosa, yet no less than in many 

 other accepted species. I have never found B. pela- 

 gica between tide-marks in the sandy bays, where 

 the other is so abundant, but only in from 10 to 20 

 fathoms, bottom mud and stones, and sandy mud. 

 Where a difference of locality concurs with a more 

 or less distinct change of character in a species, it 

 becomes important to know under what conditions 

 the change has taken place. To the geologist this 

 clue is still more important. It matters little to 

 him whether the forms are known by the name of 

 " species " or " variety " ; but it would be a loss to 

 obliterate under one appellation so valuable a dis- 

 tinction between the two. 



Genus Cheirocratus, Norman. 



CHEIROCRATUS SUNDEVALLI, Rathke. 



Gammarus Sundevalli, Rathke, Acta. Acad. Leopold., 

 t. xx. (1843), p. 65, t. iii., fig. 2. 



Lilljeborgia Shetlandica, Spence Bate and West- 

 wood, Brit. Sessile-eyed Crustacea (1863), p. 206. 



Cheirocratus Sundevalli, A. Boeck, Crust. Amphip. 

 Bor. et Arct. (1870), p. 133. 



