1908.] 147 



Ccelambus versicolor, Schall. — Abundant in large disused brick ponds at Snain- 

 (ou, but not found elsewhere. 



C. insequalis, F. — Common and general about Ayton. 



C. impresso-punctatus, Schall.— Ponds at Ayton and Snainfcon, very scarce. 

 Deronectes /a/us, Steph. — Under stones in a mountain stream near Langdale. 



D. assimilis, Payk. — In the brick ponds at Snainton only. 



D. depressus, F. — Very common in the river Derwent at Ayton. 



D. duodeeim-puslulatus, Fab.— Also in the river Derwent at Ayton, but scarce. 



Hydroporus pictus, F. — Snainton, &c. A common species. 



H. granulans, L.— This minute species occurs in some very old brick ponds 

 near the village of Seamer. 



H. rival is, Gryll. — In rapid reaches of the Derwent in Forge Valley. 



H. septentn'onalis, Gryll —In company with rivalis, though hardly so plentiful. 



H. Ihieatus, F. — Common in the district. 



H. tristis, Payk— This is abundant iu pools on the high moors. 



H. umbrosus, Gryll. — Frequent at Ayton and Seamer. 



H. angustatus, Sturm. — Frequent. 



11. gyllenhali, Schiodte.— Very plentiful iu pools on Seamer Moor. 



H. morio, Dej. — In great quantities in the trench round a barrow on Hutton 

 Eusel Moor, and in many pools on the high moors. 



S. vittula, Er. — In the Seamer brick ponds, in small numbers. 



H. palustris, L. — Very common. 



H. erythroeephalus, L. — common. 



H. rufifrons, Dufts. — Seamer brick ponds, only two examples. 



R. longulus, Muls. -This occurs in tiny rills trickling through Sphagnum on 

 the slopes of the high moors near Langdale. 



H. melanarius, Sturm. — Not so rare as supposed. I have taken it in several 

 mossy pools on the high moors. 



R. memnonim, Nic. — In many ponds, but not in plenty. 



R. nigrita, Fab.— Common. 



H. discretus, Fairm. — A few individuals in small pools. 



S. pubescens, G-yll. — Common. 



H. planus, F. — Very common. 



II. /ituratus, F. — Seamer, very scarce. 



II. ob/ongus, Steph. — Seamer brick ponds ; very uncertain in appearance. Some 

 years I have not been able to take it, while in others I have met with a score or 

 more. 



My list contains 30 species ; two more have been met with in the 

 district by other collectors, viz., ferrugineus, Steph., and obsoletus, 



Aube. 



Ponds and watercourses are disappearing so rapidly before the 

 devastating hand of improvement, that it is especially desirable that 

 records for aquatic insects should be preserved. 



West Ayton, Yorkshire : 

 June, 1908. 



