39 18 Proceedings of the Royal Irish Academy. 



the dorsal surface (11, fig. 18) a distinct groove is shown between the two 

 plates in question. In all of the Irish specimens the thick chitinous margin 

 of the dorsal plate is anchylosed with the frontal plate posteriorly. I am con- 

 vinced; however, that the specimens from the above localities are to be 

 referred to A. amplexus, as the general structure agrees well with the 

 description of that species. 



[Atractides anomcdus 0. L. Koch was not found in the Clare Island district ; 

 it is common, however, in the mountain streams of Dublin and Wicklow. The 

 epirneral area of the nymph is figured on Plate II., fig. 14c; the genital area is 

 triangular in form and carries four long, narrow discs.] 



Atractides Maglioi Koenike. 



Glendalough Lake, Connemara, September. Elsewhere in Ireland I have 

 taken this very distinct species in the River Dargle, county Wicklow, where 

 males were found in August, 1907. 



Distribution.— -Known range Germany (Koenike) ; Italy (Maglio) ; 

 Ireland. 



It may be useful to give here a synoptical table pointing out characters 

 for the separation of the six species of Atractides that have now been 

 described, more especially as I have had opportunities of examining specimens 

 of all of them from Irish localities. A table of the four German species has 

 been published by Koenike (12). 



1. Hinder part of the second frontal shield enclosed by (or anchylosed 



with) the chitinous margin of the dorsal shield, . . 2 



Hinder margin of frontal shield not enclosed, . . .3 



2. Wedge-shaped end of the first pair of epimera approaching close 



to the genital area ; shape ovate ; front margin of the body 

 straight between the eyes, . . A. amplexus Koenike. 



End of first epimera separated from the genital area by 

 slightly more than a third of the space between the capitular 

 recess and the genital area ; shape decidedly less ovate ; front 

 margin concave between the eyes, . A. connexus Koenike. 1 



3. Anal ring placed on the posterior margin of the body, 



A. Maglioi Koenike. 



4. Anal ring placed at some distance from the posterior margin, . 5 



1 The male of Atractides connexus Koenike has been found in Glendalough Lake, county 

 Wicklow, in tne momh of April. Not previously recorded from Britain. 



