102 LIMN^ID^. 



A. Shell extremely thin and fragile, and almost enveloped by 



an outer lobe or membranous expansion of the mantle : 

 sj}ire very short. 



1. LiMN^A GLUTiNo'sA*_, MUller. 



Biiccinum glutinosum, Miill. Verm, Hist. pt. ii. p. 129. Limncsus gluti- 

 nosits, F. & H. iv. p. 182, pi. cxxiv. f. 6, 7. 



Body dark grey, with a greenish -yellow tinge and bright- 

 yellow or whitish specks : tentacles very short, rather triangular, 

 with blunt tips : eyes placed on tubercles on the inner side of 

 the tentacles, very black and distinct : foot exceedingly large, 

 broad in front and obtusely rounded before and behind. 



Shell globosely-oval, so excessively thin as to be almost 

 membranous, highly polished, transparent, yellowish or greyish- 

 horncolour, with a few indistinct darker spiral zones, remotely 

 and irregularly striate by the lines of growth, which are stronger 

 towards the suture, and closely but microscopically striate in 

 a spiral direction: epidermis extremely thin: whorls 3-4, 

 globular, the last forming nearly the whole of the shell : spire 

 slightly produced : suture rather deep : mouth oval, a little con- 

 tracted above by the projection of the penultimate whorl : 

 outer lip very thin : inner lip much spread on the columella 

 and thickened at its edges : columellar fold (forming the lower 

 part of the pillar of the spire) curved and sharp.- L. 0-55. 



B. 0-45. 



Var. mucronata. Shell not quite so globular : sjnre more 

 produced. 



Habitat : Lakes and ponds in the home and eastern 

 counties, as well as in a ditch near Dunster Castle in 

 Somersetshire (Leach) ; Bala Lake (Gibbs) and a pond 

 near Windermere (Bulwer) ; but it is a local species, 

 although abundant where it occurs. Its periodical re- 

 appearance in the same spots has been remarked both 

 by Mr. Bridgman and Mr. Whiteaves to be very uncer- 

 tain and unaccountable. Specimens have been kindly 

 sent to me by Mr. Bridgman, in which the spire is more 



* SUmy. 



