fi 



422 Notes on the Crustacean Fauna of the English Lakes. 



plication of valves ; and the question suggests itself — do we, in 

 the case of L. elongatus, see a species which is undergoing a 

 gradual transformation in the same direction ? 



L. elongatus occurs in all the gatherings which I have 

 made in the Lake district, and is frequent also in similar 

 situations throughout the north of England and Scotland. 



Lynceus costatus (G. 0. Sars), seems to be a tolerably- 

 common inhabitant of lakes and clear water in moderate alti- 

 tudes, but is seldom found in more elevated and exposed 

 situations. Buttermere and Derwentwater are the only two 

 localities in our Lake district where I have met with it. 



Lynceus gutattus (G. 0. Sars). — Well marked forms of 

 this species are undoubtedly very distinct from the foregoing, 

 but I am disposed to doubt whether the differences ought not 

 to be regarded as varietal rather than specific. It is not un- 

 common in similar situations, ascending, -however, to greater 

 altitudes, and ranging from the sea-level to a height of 1553 

 feet (Angle Tarn). The following are the lakes in which I 

 have met with it : Buttermere, Thirlmere, Easdale, Langdale, 

 Angle and Sty Head Tarns. 



Lynceus testudinarius, Fischer, is a widely distributed 

 and very well marked species, and appears to haunt indiffer- 

 ently water of all degrees of exposure and elevation. It occurs 

 in my gatherings from Buttermere, Langdale, Angle and Sty 

 Head Tarns, and from pools on Eskhause, at an elevation of 

 about 2000 feet. 



Lynceus exiguus (Lilljeborg) . — A very small, but well 

 marked species,, occurring in almost all the waters of the lake 

 districts, but more commonly in those of considerable altitude. 

 I find it in Buttermere, Thirlmere, Derwentwater, Easdale, 

 Langdale, Sprinkling, Sty Head, Stickle, Angle and Floutern 

 Tarns, and in the river Brathay, below Skelwith Bridge. 



Lynueus truncatus, Miiller, is a common species in the 

 low country, and at moderate degrees of elevation in the lake 

 district, but is not so frequent in the higher mountain tarns, 

 the greatest height at which I have found it being 915 feet 

 (Easdale Tarn). It occurs also in Wiudermere, Grasmere, 

 Rydalwater, Derwentwater, Langdale, and Blea Tarns ; in 

 pools in Ennerdale, and in the River Brathay. 



Lynceus uncinatus (Baird). — This species is at once known 

 by the upturned extremity of the rostrum and strongly toothed 

 infero-posteal angle. Buttermere is the only one of the lakes 

 in which I have found it. 



Lynceus nanus (Baird), the smallest of the British Lyncei, 

 occurs at all altitudes. I have noticed it in Buttermere, in 

 Floutern, Blea, Sprinkling, and Sty Head Tarns, and in pools 

 on Eskhause and Honister Pass. 



