134 LIMNAIDA. 
6. L. TRUNCATULA (somewhat truncated) Miller. P\. VII., f. 7. 
Somewhat resembling Z. Aa/ustrts in shape, but turreted in appear- 
ance on account of the deeper sztmre; rather glossy ; south ovate ; 
umbelical cleft distinct ; whorls 5—6. A.1Iomm. B. 5 mm. 
This species is much smaller and more elegant in shape 
than the last. It is common throughout the British 
Isles both in still and running water, especially in shallow 
pools which are often dried up in summer. It is found 
further from the water than any others of this genus, 
and may be confidently searched for on the walls and 
arches of culverts and on dry mud. 
It is not advisable to carry this species in the mouth, 
as it harbours a parasitic worm, which in its after-form of 
Fasciola hepatica attacks sheep that have taken it in while 
drinking. 
Var. I. ventricdsa (Mog.). "Tumid, spire short. 
Var. II. élegans ( /Jeff.). Larger, spire tapering. 
Var. III. mzcrdstoma (Drouet). Mouth contracted. 
Var. IV. mdjor (Mog.). Larger than type. 
Var. V. minor (Mog.). Smaller, thin, dark-coloured. 
Var. VI. dlbida (Nelson). White. 
Monst. scalériforme (Jeff.). Whorls disunited. 
Sub-genus._-OMPHISCOLA Beck. 
7. L. GLABRA (smooth) Miller. Pl. VII., f. 8. 
Cylindrical, tapering gradually to a blunt point, thin, glossy, 
greyish horn-colour ; striated closely and regularly in line of growth ; 
whorls 7 to 8, rounded ; south small for the size of the shell. A. 15 
mm. 9B. 5 mm. 
