CH. VII] SNAILS AND SLUGS 237 



Family ACICULID^.- Shell small, cylindrical, thin, with long blunt 

 spire ; aperture oval ; umbilicus straight ; operculum horny ; 

 eyes sessile. 



genus Acicula Hartman, lineata (Drap.), ^-"; outer lip of shell thin, 

 inner lip spread. Beneath stones, moss, dead leaves, etc. 

 Reaches southern counties of Scotland. 



Sub-class ANISOPLEURA. 



Order EUTHYNEURA. 

 Sub-order PULMONOBRANCHIA. 



Family LIMN^EID^:. Shell spiral, hood-shaped or coil-shaped, thin, 



horn-coloured ; aperture without teeth, lip sharp ; pulmonary 



sac protected by an external lobe ; tentacles two, not retractile, 



eyes at base of tentacles. 



sub-family Ancylince, shell hood-shaped ; live attached like little 



Limpets to stones and weeds in the water. 

 genus Ancylus Geoffrey. 

 fluviatilis Mull., J" x |", apex blunt, turning to right, aperture 



oval, genital and pulmonary apertures on left side. 

 genus Acroloxus Beck, lacustris (L.), ^" x ", apex sharp, turning 



to the left, aperture oblong, genital pulmonary apertures on 



right side. 



sub-family Limnceince, shell spiral. 

 genus Limncea Lam. em. Head large, tentacles triangular, 



shell thin, horny, usually dextral ; aperture oval. 

 auricularia (L.), 1|", whorls 4 or 5, last enlarged ; spire short, 



acute ; inner lip forming small umbilical fissure behind it. 

 glabra (Mull.), f", whorls 7 or 8, spire long, aperture with broad 



internal white rib. 

 involuta Harvey, f", spire very short, sunken, suture deep, aper- 



ture pyriform. Found only near Killarney. The sole peculiar 



British species. 

 palustris (Mull.), 1", whorls 6 or 7, enlarging gradually ; spire long, 



suture deep. 

 peregra (Mull, em.), ", whorls 5, last whorl enlarged, inner lip folded 



on pillar and forming a narrow groove. 



