igiS. HuGGiNS. — Limfiaeae of West Cork Alpine Lakes. 123 



One would expect, however, in the lower lakes where 

 there was a constant influx of new blood that the local 

 races would be more or less in a state of flux, and this is 

 borne out b}/ the facts, for on carefully going over my notes 

 I find L. praetenuis is found in a lake very difficult of access 

 from below% either an isolated lake, as Caha "A," which 

 only communicates with Barley Lake some hundreds of 

 feet below, or the top lake of a series like Caha " D." 

 Similarly in Caha " B " I found a most remarkable glossy 

 thin-shelled race of L. pereger, not an example exhibiting 

 the slightest trace of variation, and as might be expected 

 Caha " B " is again an isolated mountain basin, com- 

 municating only with Barley Lake. It is also interesting 

 to note that Lough Nambrack receives only the stream 

 from the L. praetenuis Lough " D " above, and the L. 

 involuta found in this lake, though hving at no greater 

 height than those in Caha " C " scarcely half a mile away, 

 are of a constant very highly specialised form, being as 

 extremely intorted as those of Lough Crincaum and 

 beautifully polished and striated. Those found in Caha 

 " C," which receives the efliuents from Loughs " F " and 

 " H," lakes on the same level in which L. pereger abounds, 

 are, on the other hand, rougher, much more coarsely 

 striated, and display considerable variation, frequently 

 having a rudimentary spire as in Barley Lake. 



As the weather was hot I spent some time this year in 

 watching the behaviour of the animals in their native 

 places, and the three groups, " L. involuta," " L. praetenuis," 

 and " L. pereger " each have somewhat different habits. 

 L. involuta looks jet black in the water and sticks tight 

 to stones like an Ancylus,usually with its tentacles projecting. 

 It crawls very little and very slowly, clinging so firmly 

 that the stone can be lifted from the water with the animal 

 still adhering, and often it is hard to scrape it off without 

 damaging the shell. L. pereger is more active and looks 

 yellowish-brown, when a dark individual is seen in the 

 water it has a bronze-golden lustre, absent in L. involuta 

 (no doubt from the greater thickness of shell) ; while L, 

 praetenuis, which has a glistening whitish appearance in 

 the water recalling the sheen of a water-spider, is an 



