CYLICHNA. 211 



pie and brown. It is littoral in its habits, and in some 

 places the mud is lined with thousands of Ahercp. at high- 

 water mark. 



III. Cylichna. — This genus comprises little short-footed 

 BidlidcB, with eyes at the base of their flattened tentacles, 

 and small, generally white, cylindrical shells. The British 

 species are — 



C. cylindracea: shell long, narrow; apex umbilicated; spire 



concealed. 

 C, ohtnsa: shell short and thick, with a slightly produced 



spire. 

 C. nmhilicata: shell rather oval; apex umbilicated; spire 



concealed. 

 C.strigella: shell shaped like C. umUlicata; spirally striated. 

 C. conulus: shell narrow at the top, with an umbilicated 



apex. 

 C. tnmcata: shell with straight sides and flat top, showing 



the whorls of the spire. 

 C. mammiUata: shell smoother than C. truncata, T^ith the 



apex a little produced. 

 C. mtidula: shell rather oval, but tapering towards the 



apex ; spire hidden. 



IV. Amphispiea liyal'ina: a very minute, white mollusc^ 



