532 D. J. SCOURFIELD, SYNOPSIS OF THE KNOWN SPECIES OP 



COPEPODA. 



Centropagidae. 



Diaptomus Westwood. 



D. castor (Jnrine) [Schmeil (44), Brady (36)].*^ 



A widely distributed but not very common species. Not yet 

 seen in Wales, and only hitherto recorded from three localities in 

 Scotland (see T. Scott, 22). Mr. James Murray has, however, 

 recently found it also at Nerstoii Quarry, near Glasgow. 



D. gracilis Sar.«. [Schmeil (44), Brady (36)]. 



D. castor Baird (in part) (1), Brady (in part) (35). 

 D. loestwoodii Lubbock (42). 

 One of the very commonest of the British Entomostraca. 

 The " graciloides " form, whether a good species or not, has 

 never been definitely recorded as British, notwithstanding the 

 remarks on the subject by Brady (36). 



D. vulgaris Schmeil [Schmeil (44) = D. coeruleics]. 

 Only found as yet in the south and east of England. 



D. wierzejskii Ptichard [Schmeil (44) ; Brady (36) = D. serricornis']. 

 D. serricornis Brady (36), Scott (20, 23). 

 This seems to be characteristic of the extreme north of Scot- 

 land, although it occurs also in the " Highland " region. It is 

 the only species found in the Shetland Islands, if we except a 

 single record oi D. castor (23). 



D. hircus Brady [Brady (36)]. 



This species may be peculiar to the British Isles — at least, no 

 foreign localities are given by Schmeil in " Das Tierreich " (45). 

 It is closely allied to the foregoing, but the female has two setae 

 instead of one on the thirteenth joint of the first antennae, and 

 a distinctly two-jointed inner branch to the fifth pair of feet, 

 while the male has a "ploughshare-shaped process" with "an 

 obscurely fimbriated free margin " on the last joint but two of the 

 right antenna instead of a strongly serrated appendage. 



A variety, in which the process on the male right antenna 

 simply bears a pointed tooth, is widely distributed in Scotland 

 and also occurs in Ireland. Specimens of what seems to me to 

 be this variety, collected by Mr. Kane in Lough Mask, are 

 regarded by Canon Norman as D. laticeps Sars. 



* The references within square b}ackets, following the name of a species, 

 indicate where figures and descriptions of the same may be found. 



