THE LAND AND FRESHWATER HOLLUSCA OF DORSETSHIRE. 95 



its grandparents and grandchildren. Although its habits 

 are aquatic, Limncea truncatula can live out of the water as 

 long as the ground is moist, and even becomes dormant in a 

 drought, which if not of too long continuance the first storm of 

 rain will allow it to revive. This it will be seen is a feature of 

 some importance in the distribution of this Entozoon, which in its 

 earlier stages can survive a prolonged immersion. Were it other- 

 wise, and their nurses were water snails, or land snails exclu- 

 sively, the disease might be more easily stamped out. The adult 

 fluke in the sheep's liver, or that of another mammal, produces 

 about 100,000 eggs, which pass with the bile through the 

 intestines, and with the excrement are deposited among the grass 

 and herbs. When hatched they enter into the mullusc, 

 probably by boring ; the embryo then undergoes certain changes 

 and produces the germs of the next generation, which 

 instead of becoming a cercaria, the form in which it had entered 

 the sheep, an asexual embryo appears, which feeds on the tissue 

 of the snail and in the course of a couple of months a cercaria 

 is produced from the redia, which escaping from the snail, 

 encysts itself on the roots of the grass, and after being taken up 

 by the sheep in this state become developed in the adult form 

 in the liver. 



7. GLABRA, Muller pi. 7. 



HELIX OOTANFRACTA, Pult. cat., Rack, ed., p. 55, pi. 18, f. 11, 

 Brit. Conch., vol. i., p. 118. 



Body dusky-grey, with a tinge of slate colour, and minute black 

 specks. 



Shell elongated, thin,glossy, sculptured as in the preceding species, 

 greyish horn-colour, or brownish ; epidermis very thin ; whorls seven 

 to eight, slightly convex, or moderately rounded in the middle, and 

 of slow increase, the last moderately large, forming one half of the 

 shell ; spire bluntly pointed ; mouth small, acute, oblong, angular 

 above, about a third of the height of the shell, furnished with a 

 white rib inside, a little distance from the border; inner lip expands 

 towards the anterior extremity ; outer lip slightly reflected. L.0.6. 

 B.0.2. 



Hab. Ditches and ponds. In a pond or gravel-pit between 

 Lytchett and Lower Lytchett (T. Rackett). Stour, Spettisbury 

 (J.C.M.P.). 



