ge:ology of IvA saivIvE county. 



103 



SUB0RDE:R IvIMNOPHir^A — FAMILY AURICUIylD^— GE 

 GENUS CARYCHIUM, MUEEER. 



Carychium exiofuum, Say. — Shell elong^ated, taper- 

 ing-; apex obtuse; whirls five to six; suture impressed; 

 aperture obliquely oval, v^^hite; lip thick, reflected, 

 flattened, umbilicus perforated, a plait-like tooth on 

 the middle of the columella, about midway between 

 the extremities of the lip; color white, appearance 

 shining-; leng-th one and one-half mill. Dia. 6 mill. 



This minute species was described by Say as a 

 Pupa in 1822, and is still known as such to many col- 

 lectors. The most abundant of our minute species. 

 Found in wet moss, leaves, bark, drift-wood, etc., 

 along- our rivers. Dr. L. N. Dimmick collected many 

 thousands in the vicinity of Ottawa. 



EAMIEY EIMN^ID^. 



The Limnceidce are found all over the world, are 

 very variable in characters, and as yet imperfectly 

 understood. In habits they are aquatic, and are found 

 in rivers, ponds and creeks, feed on veg-etable matter 

 or the slimy material found in rivers, and on infusorial 

 animalculae. Dr. Gould speaks of them eating- each 

 other's shells in the latter part of the warm season. 

 Having- kept them alive for months at a time, I am 

 able to confirm Dr. Gould's statement as far as this. 

 They rasp off with their tong-ues the confervaceous 

 veg-etation and epidermis of each others' shells in a 

 very thoroug-h manner. The sexes are united in the 

 same individual. The shell is dextral, with a fold 

 upon the columella. They come to the surface to 

 breath free air, but are adapted to breathing- throug-h 

 water. On the approach of cold weather they bury 

 themselves in the mud for the winter. From my own 

 observation they beg-in to disappear in the early part 



