iO BRITISH PARASITIC COPEPODA. 



Male. The male is only about half the size of the 

 female. The carapace is somewhat elliptical in out- 

 line, rather longer than broad, and equal to about two- 

 thirds of the entire length of the animal; lateral 

 margins evenly rounded. Genital segment suborbicular 

 and equal to about one-third of the length of the 

 carapace. Abdomen about half as long as the genital 

 segment. Total length about 4 mm. 



Habitat. Parasitic on the gills of turbot, Rhombus 

 maximus (L.). North of Ireland (TF. Tlwmpson). 

 Polperro, Cornwall (.4. M. Norman.). Plymouth 

 (Bassett-Smith). Firths of Forth and Clyde, Aber- 

 deen, &c. (T. Scott). Irish Sea (A. Scott). 



C. B. Wilson records LepeopJitheirus thompsoni from La 

 Jolla, California, U.S.A.* 



\_Lepeoplitlieirus obscwrus Bassett-Smith. 



As there is some ambiguity concerning this form, 

 we quote the following remarks by A. M. Norman and 

 T. Scott, in c Crustacea of Devon and Cornwall,' 

 p. 208 : " Mr. Bassett-Smith (' Journ. Marine Biol. 

 Assoc.,' vol. iv, 1896, p. 157) records a species from 

 the brill (Rhombus Idevis) taken at Plymouth, and 

 refers it with doubt to Lepeophtheirus obscurns Baird, 

 which was obtained from the same species of fish. 

 Subsequently Bassett-Smith figures what he then 

 styles C aligns obscurns Baird (' Ann. and Mag. Nat. 

 Hist.,' ser. 6, vol. xviii, pi. iv, fig. 2), and not only is 

 his parasite there referred to the genus Caligus, but 

 the figures show the presence of sucking -disks. 

 Whether the form he found was a Lepeophtheirus or a 

 Caligus, it was certainly not Lepeophtheirus obscurus of 

 Baird. In Bassett- Smith's third paper (' Proc. Zool. 

 Soc.,' 1899, p. 456) he referred it back again to the 

 genus Lepeophtheirus. It is just possible, if the species 

 he found was a LepeopJitheirus, that it may have been 

 the female of L. appendiculatus Kroyer (' Naturhist. 

 Tidssk.,' ser. 3, 1863, p. 207, pi. vi, fig. 4, a-i) 9 which 



* ' Proc. U. S. National Museum/ vol. xxxv, p. 441 (1908). 



