TAYLOR: ON NEW VARIETIES OF BRITISH SHELLS. 37 



Neritina fluviatilis var. cerina Colbeau. Shell of a uniform 

 straw-yellow color. 



Found in the Avon canal near Bath, by Miss 

 F. M. Hele, to whom science is indebted for many 

 valuable discoveries, and to whose accustomed 

 generosity I am indebted for specimens. 



Valvata piscinalis m. sinistrorsum n. m. Shell reversed. 



Found by Mr. Groves at Sunbury, and recorded 



by Dr. Jeffreys in the Ann. and Mag. Nat. Hist, for 1878. 



Planorbis lineatus var. albina n. v. Shell milk white and 

 semitransparent. 



Found in ditches near Deal by Mrs. Fitzgerald, 

 who has obligingly given me a specimen. 



Planorbis complanatus m. sinistrorsum n. m. Shell 

 reversed. 



Miss F. M. Hele has been so fortunate as to find 

 this at Wye, in Kent. 



Septa of Planorbis lineatus. — Dr. Jeffreys (British 

 Conchology, vol. i., p. 80) in speaking of this species says that 

 the septa are "only formed in adult individuals." I have 

 however found them in half-grown shells, and this observation 

 was also made independently by Mr. Butterell and communi- 

 cated to me. In some of the specimens the dried body of the 

 animal had shrunk beyond the second septum. I have not 

 noticed whether during life they have that power. Dr. Jeffreys 

 remarks " that the septa form half closed chambers, and the 

 animal retreats into the front one for safety." — J. W. Taylor. 



