130 



HARDWICKE'S SCIENCE-GOSSIP. 



[June 1, 1S70. 



theory is the fringed margin of the pitcher. On the 

 whole, we incline to the opinion that the pitcher is 

 simply a reservoir, in which, in times of plenty, the 

 surplus fluid may be stored for the future use of the 

 plant, and that the glands serve in the one case to 

 excrete the fluid, and in the other to reabsorb it ; or 

 it may be that the fluid is intended to attract insects 

 to the plant, that, after they have satisfied their 

 thirst, they may visit the flowers and aid in their 

 fertilization. 



We have now only time to mention that our 

 scientific equanimity was sorely tried during our dis- 

 sections by the presence of some form of tannio- 

 gallic acid, which, acting upon our cutting instru- 

 ments, struck an intense black, spoiling our sections 

 and not improving our instruments. However, we 

 revenged ourselves by getting portions of the stem 

 bruised, boiled with water, and tested with per salts 

 of iron, by way of satisfying ourselves that the source 

 of our trouble was really a misplaced black ink 

 factory. 



There are still many points left unnoticed upon 

 which we would have liked to have written, but we 

 will conclude by commending Nepenthes to the at- 

 tention of our readers. H. Pockxington. 



NEW BRITISH SHELLS. 

 By J. Gwyn Jeffreys, F.R.S. 



I LATELY received from Mr. Thomas Rogers, 

 an active and enthusiastic naturalist at Man- 

 chester, specimens of a small Planorbis, for my 

 opinion. He discovered them in the Bolton Canal. 

 They proved to belong to a species new to Europe, 

 viz. the P. dllatatus of Gould (P. lens, Lea), which 

 was originally found near Cincinnati, and inhabits 

 an extensive tract of the United States. The shell 

 is about the same size as P. naut ileus, 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 expanded (" so as to make it trumpet-shaped," — 

 Gould), and the umbilicus is abruptly contracted, 

 small, and deep. Some of the Manchester speci- 

 mens are more or less distinctly, though micro- 

 scopically, striated in the direction of the spire. 

 The following is a description of the animal or soft 

 parts : — 



Body dark grey, often with a slight orange tint, 

 closely and minutely speckled with flake-white : 

 mantle thick, lining the mouth of the shell : head 

 large and tumid : mouth 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 be- 

 hind : verge curved, on the left-hand or umbilical 

 side of the shell. The spawn is arranged in an 

 irregular mass containing about a dozen mem- 

 branous 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. 



Inhabits the Bolton and Gorton Canals at Man- 

 chester. 



Suspecting that this American species had been 

 introduced into our canals through the cotton-mills 

 I wrote to Mr. Pcogers for information ; and he 

 tells me that in one habitat (and probably in the 

 other also) the waste from the first process or 

 " blowing-machine " is discharged close to that part 

 of the canal where the Planorbis occurs. As the 

 best cotton is cultivated in river-bottoms, and the 

 crop, when picked, is spread out and dried, nothing 

 is more likely than that it should take up either the 

 Planorbis or its eggs ; and these could be trans- 

 ported alive to any distance. The vitality of Pla- 

 norbis, and its capability of enduring considerable 

 changes of temperature, may be inferred from the 

 habit which certain species are known to possess 

 of closing the mouth of the shell in summer (when 

 the shallow pieces of water in which they live are 

 dried up) with an epiphragm or membranous lid, to 

 exclude the heat and prevent the evaporation of 

 the natural moisture. Thus protected, they keep 

 alive for weeks, and even months, until the return 

 of the rainy season. 



In connection with the foregoing, I would 

 suggest that Sphcerium ovale may have been intro- 

 duced in the same or some other way from the 

 United States. That species also inhabits the 

 canals near Manchester, and may be the Cyclas 

 transversa of Say. It has long been known in this 

 country. I have a specimen which was in Dr. 

 Turton's collection of British shells more than 

 forty years ago. 



I have written to Mr. Anthony, of Cambridge, 

 Mass., one of the leading conchologists in the 

 United States, for information as to the range of 

 distribution there of both these species, and 

 especially as to whether they, or either of them, 

 inhabit the cotton-growing districts. 



Several species of land shells (e. g. Zonites 

 cellarius and Helix nemoralis, var. hortensis), and 

 perhaps of freshwater shells also, are supposed to 

 have been introduced into North America from 

 Europe by the agency of man, and are now 

 thoroughly acclimatized in the former continent. 



My correspondent, Mr. Thomas Rogers, of Man- 

 chester, has added another species to this well- 

 worked department of our fauna. Specimens of a 

 Zonites which he has now sent me, collected by him 



