JOURNAL OF CONCHOLOGY. 127 



Ancylus lacustris a Thread-spinner. — My valued 

 correspondent, Mr. T. D. A. Cockerell, has communicated to 

 me the interesting circumstance that this species has the power 

 possessed by many other of the Limnseid^e of spinning a mucus 

 thread. — He says "I have just been watching a young specimen 

 of Ancylus lacustris spinning a downward thread." According 

 to the rough but characteristic sketch of the circumstance made 

 by Mr. Cockerell, the thread was about half-an-inch long, 

 attached to the extremity of a leaf of the Anacharis, the body 

 of the animal being bent during the operation, the head and tail 

 nearly close together. — J. W. Taylor, Aug. 15th, 1S83. 



Paludina vivipara v. unicoior Jeff. — Dr. Jeffreys, in 

 ' British Conchology,' vol. i. p. 58, describes the bandless form 

 of this species under the name of Faludma vivipara v. unicoior, 

 characterizing it as "without bands," and in quoting the locali- 

 ties says : " The variety has been found by Mr. Pickering in 

 Hertfordshire, and by myself in the Thames at Richmond.'' 



Mr. Pickering, who appears to have first discovered this 

 variety, and whose find is quoted as above by Dr. Jeffreys, 

 fully described it in 1847 in the 'Zoologist,' p. 1786, and be- 

 stowed upon it the name " efasciata " in an article entitled 

 " Description of a New Species or Variety of British Paludina." 

 In that communication Mr. Pickering says "the shell is per- 

 fectly bandless, both externally and internally, in all stages of 

 growth. It has 5 J^ volutions in the adult state : the colour is 

 a bluish-green when alive with the animal in it, changing to 

 yellowish-green after the animal has been removed and the 

 moisture of the periostraca thoroughly dried up : inside light 

 bluish-white, and the lip edged with dark-brown. The shell is 

 very local and by no means plentiful. I have taken it in slow 

 streams in Hertfordshire for the last three years successively, 

 but nowhere else. I have never met with any specimens that 

 are intermediate between it and the strongly banded ones, but 



