BELONGme TO DA.PHNIA AND OTHER ALLIED GENEEA. 223 



and rather densely pubescent.*'' The ventral margin of the valves 

 (fig 6) is densely beset from the antennal notch to near the 

 posterior margin with very long, fine hairs, some of which are 

 plumose. Length, 1'6 mm. 



This is a very generally distributed species — not only in the 

 British Islands but on the Continent, inhabiting ponds, ditches, 

 and small weedy pools rather than the larger expanses of lakes, 

 where its place seems to be generally occupied by D. longispina 

 or other allied forms. It is noted by almost all European authors, 

 and Mr. Herrick styles it the " commonest of Daphnias " in the 

 United States. But the specific name pulex having been applied 

 to the commonest and first-described species, it is more than 

 probable that other allied forms have been included, especially 

 .by the earlier authors, under the one specific name. Even more 

 than in most other Baphnim great allowance must here be made 

 .for variation in almost all directions. The amount of reticula- 

 tion, shape and size of the shell, especially as to the projections 

 of spine and rostrum, are very inconstant even in specimens from 

 the same locality, while in those from different places the varia- 

 tions are, of course, liable to be greatly accentuated. 



The drawings here given were made in the case of the female 

 from specimens taken at Shotton (county Durham), those of the 

 raa.le from a pond at Whipscross Road, Essex. These latter 

 were kindly sent to me by Mr. D. J. Scourfield, F.L.S. 



Tar. brevispina (Daday de Dees). 



1888. Daphnia hrevispma, Daday de Dees, Crustacea Clado- 

 cera I'aunae Hungaricse, p. 119, pi. IY-, figs. 13-15. 



- Mr. D. J. Scourfield has sent to me specimens taken in the 

 .neighbourhood of Birmingham, which are different in some re- 

 spects from the ordinary form of D.jndex, and I think are the same 

 .as those described by Daday de Dees under the specific name 

 brevispina. They do not, however, appear to me to require more 

 than a varietal name. The spine is rather longer than that 



* The verticillate arrangement of the hairs described by M. Jules Richard I have not 

 been able to make out, except indistinctly in one specimen. 



