04 A REVISION OF THE BRITISH SPECIES OF 



from whose memoir the figures 10 and 13 in PL XIV. are like- 

 wise copied. 



Females, and a few immature males, of D. bacillifer occurred 

 somewhat sparingly in a gathering made by the Eev. Dr. Norman 

 at Loch Earn Head, Perthshire, near the middle of the lake. 

 In the same collection occurs also D. gracilis in great numbers, 

 and it is by no means easy in the younger forms to separate the 

 two species ; but in the adult condition, D. bacillifer is easily 

 recognized by its somewhat stouter build and by the shorter 

 antenna?. D. bacillifer was described by Wierzejski in 1882 as 

 a variety of D. gracilis, but in 1887 was re-named by that author 

 as D. montanus ; the term bacillifer, however, previously pro- 

 posed by Koelbel having the claim of priority. 



D. bacillifer is noted by Prof. Lilljeborg as having been taken 

 in Siberia during the Nordenskiold Polar Expedition ; amongst 

 the Tatras (Carpathian) Mountains ( Wier%ejski) ; in the Balaton 

 Lake, Hungary {Koelbel) ; in Einmark ( G. 0. Sars) ; and in the 

 lakes of Gimont and Cristol, near Brianc^on, at a height of about 

 2,400 metres {Dr. R. Blanchard). 



There is so little, on a cursory glance, to distinguish this 

 species from D. gracilis, that it is very likely it may have been 

 often overlooked amongst lake gatherings from mountainous 

 regions. I can scarcely doubt that I have done so myself, and 

 that it will be found to occur not unfrequently in such localities. 



4. Diaptomus Sancti Patricii, n.sp. (PI. XIV., figs. 5-8). 



Posterior angles of the last thoracic segment very much pro- 

 duced so as to form attenuated spines. Anterior antenna? reaching 

 about as far as apex of furca : penultimate joint of the anterior 

 antenna of the male entirely destitute of marginal process. Inner 

 branch of the fifth pair of feet in the female indistinctly Particu- 

 late, nearly as long as the first joint of the outer branch, and 

 bearing three minute apical seta?. Last joint of the outer 

 branch small, the larger apical seta not reaching as far as the 

 extremity of the claw of the penultimate joint. Inner branch 

 of the right fifth foot in the male simple, mucronate at the apex, 

 and reaching beyond the middle of the last joint of the outer 



99 



