Clare Island Survey — Aquatic Colcnptera. 29 1 1 



Helophorus aquaticus, L. — Louisburgh ; Westport. 



viridicollis, Steph. (acneipennis, Thorns). — Belmullet (A. W. S.); Curraun ; 

 Louisburgh ; Westport. 



affinis var. griseus, Herbst. — Louisburgh ; Westport. 



granulans, L. — Belmullet (A. W. S.) ; Louisburgh ; Westport. 



brevipalpis, Bedel. — Curraun ; Louisburgh ; Westport. 

 Octhebius viridis, Peyron. — Westport (J. N. H.). 



pygmaeus, F. — Westport. 



bicolon, Germ. — Curraun; Louisburgh; Westport. 



punctatus, Steph. — Curraun. 



lejolisii, Bey and Muls. — Louisburgh. 

 Hydraena testacea, Curt. — Louisburgh. 



riparia, Kiu/. — Louisburgh ; Westport. 



gracilis, Germ. — Louisburgh. 

 Cyclonotum orbiculare, F. — Louisburgh ; Westport ; Castlebar. 



The only other parts of West Mayo for which I have any records are 

 Caher Island and Inishturk from which Mr. Stelfox brought me a few 

 specimens after his visit last July. From the former I have two species : — 

 G. inaequalis and A. sturmii and from Inishturk I have three : — H. lituratus, 

 G. natator and 0. lejolisii. 



From the inequality in the time spent in the different districts it would 

 not be possible to make any comparison of the separate faunas, but what 1 

 said with regard to the habitats on Clare Island will explain any differences in 

 the mainland districts. For instance, a number of species occurred on the 

 Curraun peninsula and about Louisburgh which were not found at Westport 

 merely because no peat moss was worked in the latter district. So far as I 

 know, geological conditions have little or no direct effect upon the water- 

 beetle fauna. Where the conditions are such as to produce acid humus, the 

 oxylophile fauna occurs, while in areas of good drainage the helophile fauna 

 dominates. But peat-mosses occur even in limestone areas and are not 

 peculiar to any particular geological conditions, although some rocks may be 

 better suited to their formation than others. 



With regard to the relationship of the Clare Island fauna to that of the 

 mainland, it possesses one species, Hydroporus celatus, which was not found 

 anywhere else but which almost certainly occurs wherever a suitable habitat 

 exists. It is by no means a rare species but the small trickling streams in 

 which it normally lives are easily passed over and thus the species seems to 

 be scarce. There is, therefore, nothing peculiar about the Clare Island water- 

 beetle fauna as compared with that of the mainland. The total of forty-seven 

 species compares favourably with that of other islands I have worked ; on 



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