48 LIMNJEIDjE. 



of Natural History' for November, 1869, gave the 

 following description of it : — 



" The shell is about the same size as P. nautiletis, 

 which may be considered its nearest ally ; but it has 

 one whorl less, the periphery is angulated, the under 

 side is remarkably gibbous, the mouth is very large, 

 squarish, and scarcely oblique, the outer lip is ex- 

 panded (* so as to make it trumpet-shaped ' — Gould), 

 and the umbilicus is abruptly contracted, small, and 

 deep. Some of the Manchester specimens are more 

 or less distinctly though microscopically striated in 

 the direction of the spire. The following is a de- 

 scription of the animal or soft parts : — 



" Body dark grey, often with a slight orange tint, closely and 

 minutely speckled with flake-white ; ?nantle thick, lining the 

 mouth of the shell ; head large and tumid ; vi02ith furnished 

 with broad lobular lips ; tentacles cylindrical and extensile, 

 widely diverging, broad and triangular at the base ; the sheath 

 or outer part is gelatinous, and the core or inner part is of a 

 much darker colour and apparently greater consistence ; tips 

 rounded ; eyes sessile on the inner base of the tentacles ; foot 

 oblong, squarish in front and bluntly pointed behind ; ve7'ge 

 curved, on the left-hand or umbilical side of the shell. The 

 spawn is arranged in an irregular mass containing about a 

 dozen membranous capsules, each of which has a yellowish yolk 

 or vitellus in the centre. 



" It is active, and occasionally creeps, like many 

 other aquatic Gastropods, on the under surface of the 

 water, with its shell downwards." 



In the 'Quarterly Journal of Conchology' for 

 August 1875 there is an extract from a paper read by 

 Mr. Rogers in 1870 before the Natural History Section 

 of the Manchester Literary and Philosophical Society, 

 upon the introduction of this species, in which he " said 



