78 LESSON XI. 



with numerous transverse striae of a light colour 

 approaching to white, and giving it some resem- 

 blance to veined wood ; sometimes it has one or 

 two oblique bands ; inside white, glossy ; aper- 

 ture large, extending the whole length of the 

 shell, somewhat contracted towards the upper 

 part ; columellar lip smooth ; it has no external 

 convolutions, but at the top is depressed, and 

 has a small umbilicus ; it is usually about two 

 inches long, and one and a quarter broad at the 

 base. 



This is one of the Bull 33 which possess a 

 gizzard.* In this animal it consists of two 

 triangular, thin, testaceous plates nearly an inch 

 in diameter, and another of an elongated semi- 

 cylindrical form. These platos are connected 

 together by a tough yellowish ligament. Within 

 or near this powerful digestive organ have been 

 found the smaller tribe of testacea, and also the 

 powder of their shells in considerable quantities. 



This is the largest species of the British 



Bull. 



BULLA Fontinalis.] 

 STREAM DIPPER. 



Specific character. Shell sinistral, having 

 four or five reversed volutions, glossy, pellucid,J 

 and of a light horn colour; the body whorl is 

 large ; the others are very small, and not much 



* Plate II. fig. 7. f Plate II. fig. 9. 



{ Pellucid, so clear that the light is seen through it. From 

 JLaiin, per through, and lux light, 



