Mr. W. II. Benson on Camptonyx. 337 



have been perhaps regarded as a Pileopsis ; in fresh water, it 

 might have been taken for an aberrant form of Ancylus. The 

 circumstance of the shell not being internal prevents its asso- 

 ciation with Parmacelln ; while the smallness of the testaceous 

 part of Ti'stacelln and PlectrujiJiorus, compared with their animals, 

 forbids their union with a genus in which the animal is com- 

 pletely covered by the shell, and adheres thereby to flat surfaces. 

 Nevertheless it is probable that Cumptonyx holds an interme- 

 diate place between those genera and Succinea, and that it bears 

 the same relation to the latter that Ancylus does (through the 

 intermediate Indian genus Camploceras) to Lymnaa. 



The external rib and furrow on the shell have a correspond- 

 ing depression and ridge internally, but they are less strongly 

 marked. In the animal the sole is oblong, of a pale colour, 

 transversely corrugated, and surrounded on all sides by a thick 

 greyish hyaline mantle, which completely hides the sole during 

 aestivation, exuding a gluten most tenacious when dried, and 

 which even twenly-four hours' immersion in w^ater, tepid when 

 first applied, failed in some instances to dissolve. The animal 

 cannot be induced to exhibit tentaeula or ocular points either 

 by steeping in water or by manipulation with a camePs-hair 

 pencil. There is a slight appearance of two nipples, or a bilobed 

 muzzle, above the narrow fore-end of the sole. 



The colour of the cavity of the shell is a rich purplish ochre, 

 and the general aspect betokens rather an inhabitant of the land 

 than of fresh water. Some of the Succinece found with it have 

 precisely the same tinge within the aperture, and have been 

 cemented to rocks by a very tenacious substance. Mr. Theobald 

 was doubtless justified by the situations in which he found his 

 specimens — on a high peak, where the drought, at the time of 

 his visit, had driven the largest examples of the gigantic Succinea 

 into inaccessible crevices in the rocks, — in attributing terrestrial 

 habits to the animal. It appears probable that Camptonyx only 

 moves in search of food during the height of the rainy season, 

 when the air is saturated with warm moisture, and that its habits 

 are very sluggish. 



I have neither the instruments nor the practice necessary for 

 an anatomical examination of specimens so small as those which 

 have reached me with the included animal, and have therefore 

 taken measures for putting them into expert hands. Whether 

 the form may eventually be referred to the Helicida or to a 

 station near Ancylus, or prove to be the type of a new family, I 

 am of opinion that the characters of the testaceous covering 

 will justify the formation of a separate genus for its reception, 

 and on that account I have considered it advisable not to 



Ann. i>^ Mag. N. Hist. Ser. 3. Vol.'i. 22 



