58 



4. Limmra vipgasoma, Sui/. This toautiful and distinct Kpecies was first 

 found in Meech's Lake by Mr. Latchford, in September, 1880, and a good 

 aeries was £(!cured during the past season. This species is the largest of the 

 Limnividir:. In beauty it is surpassed only by such exceptionally fine forms of 

 L. slagnalis as occur here in the Kideau Canal. L. megasoma is easily distin- 

 guished from all other American species by its ovate form, thick shell, and rich 

 chestnut-brown interior. Haldeman has made it the type of his sub-geuus 

 Hulimnxa. It is a northern species ranging from Vermont to Lake Superior, near 

 which it was first found by Dr. Bigsby. It was once abundaot in a pond on 

 ^un's Island, in the St. Lawrence, opposite to Montreal, but of late years it 

 appears to have become almost extinct in that locality. 



5. Limntca lanceata, Gould. Three specimens of this species were found by 

 Mr. Fletcher, in Dow's Swamp in September last ; previous to this no one but 

 Agassiz appears to have observed it either in Canada or elsewhere. As late as 

 1865, the date of Binney's monograph on the American Lim7ueid<v, there was 

 only a single specimen in the cabinet of the Smithsonian Institute at Washing- 

 ton. The locality of the shells found by Agassiz, and named by his triend Dr. 

 Gould, was " Pic Lake " to the north of Lake Superior. The shell of L. 

 lanceata is very fragile and slender. It not a little resembles L. {Acella) gracilis, 

 Bay. 



6. Limmea caperata., Saij, \^x.vmbilicata, Adams. By some authors this shell is 

 regarded as merely a variety of L. caperata, Say ; Adams, however, with others, 

 claims toat it is a distinct species and calls it L. umbilicata. According to 

 Binney, who, following Haldeman, favours the former view, '-It is found along the 

 northern tier of States to Michigan ; has been quoted from Louisiana; catalogued 

 by Adams from Jamaica, and placed by Poey in the synonymy of X. cubensis, P/r." 

 It would appear, therefore, to be a very constant variety, if, indeed, it be not a 

 distinct species. Adams acknowledges that it resembles L. caperata, Saj/, but 

 observes that in Say's species "the aperture is but one-half the length (in 

 " umbilicata it is three-fifths) the revolving lines are raised, more distinct and 

 " numerous, the umbilicus is rather less, and there is one more whorl." In this 

 locality Say's species is abundant, but Adams' is very rare — only three 

 specimens having been obtained so far. They were found in the Kideau Kiver 

 at the Eitle Kange by Mr. Latchford. They were sent to Mr. Tryon for examina- 

 tion and returned marked " L. caperata, Say, var. umbilicata.^' 



7. Limmea emarginata, Say. There once existed considerable doubt with re- 

 spect to this variable shell and its identity with L. catascopium. Specimens in Mr. 

 Heron's collection bear the latter name. It is now, however, very generally 

 regarded a-< a distinct species. L. emarginata is a thicker, larger, and considerably 

 wider shell than L. catascopium. It is a common Fhell near rapid water in the 

 Ottawa and Rideau Rivers ; very fine specimens are to be found about a mile above 

 Billings Bridge. The true L. catascopium is less frequently found, being noted 

 only from Brigham's Creek, Nepcan Bay, and at the Chats Rapids, near Arnprior. 



8. Limnfca lepida, Gould. One of the most interesting additions to the list is 

 the above named shell which was found in Meech's Lake by Mr. Latchford in 

 September. The naming of Mr. Latchford's specimen ha^ been checked by Mr. 

 Tryon and found correct. The specimen found difters from Binney's figure only 

 in the slighter convexity of its whorls. Irs size is exactly that of the shells 

 described by Dr. Gould, 5 inch by ^ inch. L. lepida has heretofore bten found 

 only in Oregon. It is very rare. 



9. Physa gyrina, Say. This widely distributed species differs from P. hetero- 

 stropha in having a more elongated spire and a less deeply indented suture. It is 

 louud plentiful during the spring months, in ponds near tlie Canada Paciric Rail- 

 way at Mechanicsville. 



10. Ancylus parallelus, Haldeman. Tliis fresh water liuipel has been found in 

 the Ottawa River and Rideau Can il, adhering to tue subniergeil leaves of water 



