302 TAYLOR : VARIATION OF LIMN.^A PEREGRA. 



and of a milk-white colour,' is identical. Other names be- 

 stowed upon this variety are albinos by Baudon and Van-den- 

 Brqeck which refer to the same peculiarity but in shells of 

 different form. The name albida has also been applied to 

 this variety by several authors. 



Var. picta Jeffreys. Shell beautifully mafked spirally by alternate bands of 

 brown and white. 



This variety is characterized by the presence of white 

 or whitish lines revolving with the spire and alternating 

 with the ordinary ground color of the shell. I have already 

 in the present paper expressed my views as to the origin of these 

 markings in the majority of cases. 



In other specirnens transverse linear markings traverse 

 the shell in an opposite direction to those of var. picta^ as is 

 well shown in the var. gibilmannica figured by Sowerby, and 

 very characteristically by Tryon's var. zebra in the closely allied 

 species L. paliistris. I have also a similar specimen of B. 

 tentaculata, showing the same disposition of markings, but 

 caused by undoubted disintegration of the shell substance at 

 remarkably regular intervals. 



Var. diaphana Parreyss. Shell very thin and transparent. 



The most beautiful and characteristic specimens of this 

 pretty and delicate shell that I have myself seen are some pro- 

 cured from an engine-cistern at Burnley by Mr. R. Wigglesworth. 



The Z. membraiiacetis Porro agrees with this form in its 

 great delicacy of shell. The vars. pelbtcida Gassies, tenuis 

 Brown, tenera Parreyss, and tetier Ziegler, are all intended to 

 distinguish the same peculiarity. The var. podliuntensis Bayer 

 is stated by Westerlund to be identical with tenera Parreyss. 

 The L. succinea of Nilsson may also be practically the same, 

 the author comparing it for colour, lustre, and transparency 

 with Physa fontinalis, 



J.C, vi., Jan,, 1B91, 



