THE NEEDLE AGATE SHELL. 63 



mistaken by the uninitiated for little white maggots, 

 the shell being long, thin, and cylindrical, and rather 

 smooth. The Swedish naturalist, Nilsson, who has 

 given a good description of this mollusk, observed that 

 through the transparency of the shell the irregular 

 motion of its breathing could be easily seen with a 

 glass, and that when the respiratory cavity was shut the 

 motion ceased, but was continued when the chamber 

 was reopened ; and he compared this alternate expan- 

 sion and contraction of the breathing organ in this 

 snail to the pulmonary action of vertebrate animals. 

 He supposed that it fed on the tender and jucy fibrils of 

 the roots of grass. The little sedge shell, Carychium 

 minimum, may be looked for at the roots of grass and 

 other plants, and amongst moss in damp situations. 

 Specimens have been found on the roots of the 

 Iris pseudacorus at Hammersmith, and in winter 

 it may be discovered in the hollow stems of the 

 larger umbelliferous marsh plants. From its very 

 minute size, being one of the smallest of our land 

 shells, a very careful search for it is necessary. In 

 appearance the shell is not very unlike Pupa, already 

 described, but is more transparent, with fewer whorls, 

 and has the spire less blunted (PL VIII., fig. 4). 



