272 TAYLOR : GUERNSEY AND SARK MOLLUSCA. 



Planorbis spirorbis v. ecarinata Jeff. — These specimens 

 are very interesting. They are the P. spirorbis of Conti- 

 nental authors, differing from the typical P. spirorbis of 

 British authors (which is considered by foreign concholo- 

 gists a distinct species under Poiret's name of P. rotundatus) 

 in the absence of carination and a lesser number of whorls. 

 Dr. Jeffreys in his valuable work does not allow this form 

 specific rank, but describes it as var. ecarinata, adding a 

 subsidiary colour character to the description, presumably 

 to more accurately describe the British specimens. The 

 Guernsey specimens are of a brownish horn colour, have 

 from 4^ to 5 whorls, and are 4^ mill, in diam , and 

 I mill, in height or thickness. 



Planorbis vortex (L). — There are two specimens of this ; 

 one not quite mature, the other larger than average speci- 

 mens, but flatter than usual. Dr. Jeffreys gives the 

 average dimensions as 5)^ mill, by i^. The Guernsey 

 shell is 9 mill, broad, and with an altitude of only i mill. 



Physa hypnorum (L.). — Mr. Tomlin sent two of this species. 

 They were of ordinary size and aspect, but were accident- 

 ally crushed before I had taken note of their peculiarities. 



Limnaea peregra v. ovata Drap. — The specimens are a small 

 form of V. ovata, but have a shorter spire than the fully 

 characteristic form of that variety. The dimensions are 

 total length 11 mill., width 10 mill. The measurement of 

 the aperture is 8^ x 5 mill. 



Limnaea palustris (Miill.). — Are proportionately stouter than 

 typical specimens. Dr. Jeffreys gives the average dimen- 

 sions of this species as length 25 mill., diam. 10 mill. The 

 Guernsey specimens are only 16 mill, in length, while their 

 diameter is ti mill. The aperture is 8 x 31^ mill. The 

 shells are faintly spirally ridged, and have the purplish 

 mouth of V. tincta, to which variety these specimens may be 

 referred, though hardly having all necessary peculiarities. 



J.C, iv., Jan., 1885. 



