210 



a proof of a difference in species, while it may be 

 the cause of the variation. 



The eggs are like those of L. stagnalis. (See 

 Pfeiffer, t. 8. f. 18.) 



These animals are extremely variable in size and 

 colour, according to the locality in which they are 

 found, and the abundance of their food. 



Mr. Alder observes that a variety of a much 

 smaller size is found on the margins of rivers, and 

 another is found in mountain streams. 



94. 5. LIMNAEUS truncatulus. Ditch Mud Shell. 

 Shell oblong-oval, pointed, brittle, perforated, 

 with six or seven rounded and deeply divided 

 volutions, striolate longitudinally and across ; 

 mouth ovate-oblong, (t. 9. f. 108.) 



Helix fossaria. Mont. p. 372. t. 16. f. 9. ; Linn. Trans, viii. 

 t. 5. f. 9. Buccinum truncatulum. Muller, Verm. ii. 130. 

 Helix truncatula. Gmelin, 3659. ; Dillw. R. S. 967. 

 Limneus minutus. Drop. p. 53. t. 3. f. 5, 6.; Alder, Col. 115. 



Bulimus truncatus. Brug. E. M. i. 310. Limneus fos- 

 sarius. Turton, Man. ed. 1. 124. f. 108. Lymneus minutus. 

 Brard, p. 138. t. 5. f. 8, 9. Lymnaea minuta. Lamarck, 

 vi. ii. p. 162. Stagnicola minuta. Leach, Mollusc, p. 143. 



Lymnaea fossaria. Flem. Edinb. Ency. vii. 77., B. A. 

 274. Limneus truncatulus. Jeffreys, Linn. Trans, xvi. 

 377. Limnaeus minutus. Rossm. Icon. i. 100. t. 2. f. 57. 

 Bulimus obscurus. Pioret, Prod. 35. Limnophysa minuta. 

 Fitz. 113. Limnaeus truncatulus. Forbes and Hanley, 

 B. M. iv. 177. t. 124. f. 3. Lymnea minuta. Schub. and 

 Wagner, f. 4. t. 34, 35. Limnaeus limosus. Cantr. Mem. 

 Brux. 1836, 157. Limnea minuta. Grass. Moll. Franc, t. 4. 

 f. 44. Limnaea truncatula. Alder, Moll. 42. Lymnea 

 oblonga. Pat. Moll. Vog. 60. Limnea microstoma. Drouet. 

 Limnea Doublieri. Req. 



Var. 1., conic-oval, less glossy brown and smooth. Drop. 



p. 53. t. 3. f. 7. 

 Monstrosity with the lower volution flattened at top, in the 



centre of which are sunk the other volutions. 



