57 



As the outline of shell after shell was cast upon the screen, each was o'b.'served to 

 be decidedly asymmetrical and unequally curved on the sides. The young of 

 U. luteolus and U. borealis proved aNo to bd inequilateral ; and I have little 

 doubt that the same want of symmetry obtains in the young of almost all other 

 species. It seems, therefore, that Dr. Lea was mistaken in describing and 

 figuring as symmetrical the embryonic forms of many speci'-s of tire Uaionidfe. 

 With ^4. JlaviatiUs closes the record of the species so far observed here. Ex- 

 tended as it is, for a pl^ce so distant from the metropolis of the IJnionidx in 

 the Oliio Valley, it does not in my opinion include all the forms that occur in this 

 vicinity. A. plana^ Lea, and A. Ferussaciana, Lea, probibly occur here ; and 

 when the numerous lakes and streams around our city ar-t more diligently 

 searched, they will, I feel confident, furnich very miterial additions to the 

 present li t of the Ottawa Unionklx. 



Report of the Conchological Branch. 



For the Season of 18S2. 



To the Council of the Ottaioa Field-Naturalists' Club : 



The undersigned beg leave to report that in this branch of the Club, nine 

 members have been engaged in active work during the season, and that the 

 researches made, (particularly by Mr. Latchford,) have been of a most thorough 

 nature and have resulted in additions to the list of shells already recorded in 

 this locality, and the discovery of some which may prove new to Canada itself; of 

 these, a list is appended in which all are mentioned of which the identity has 

 been proved without doubt. Descriptive notes of twenty-seven species em- 

 braced by the family Unionidee will be given by Mr. Latchford, in a paper which 

 he is preparing on that subject to be read before the Club. 



H. B. SMALL, 



P. B. SYMES, 



Leaders of the Conchological Branch. 



APPENDIX. 



Descriptive notes of shells found in the vicinity of Ottawa during the sum- 

 mer of 1881, not before recorded on the Club list : — 



1. Amnicola limosa, Say. This shell is abundant in ponds near St. Louis 

 Dam. In Mr. Heron's collections (presented by him to the Ottawa Literary and 

 Scientific Society,) it is marked '' A. porata, Say." The true A. porata of Say is, 

 however, quite a different shell ; but the A. porata of Gould is a synoym of A. 

 limosa, Say. The true A. porata Say is to be found in several lakes in Ottawa 

 County. It is larger and more globose than A. limosa, Say, to which it is allied, 

 and has a more distinct umbilicus. Its distribution too is more limited, being 

 confined to the Northern States and Canada. 



2. Amnicola decisa, Ilaldevian. Specimens of this shell have been found in 

 Leamy's Lake. It has the labium more appressed than in any of the other 

 species of the genus found in this locality ; the form too is more elongated. It 

 was found by Mr. Heron subsequent to the publication of his list. 



3. Pomatiopsis Cincinnatiejisis, Lea. (^Amnicola Sayana, Anthony.} A few 

 specimens of this species have been found in Dow's Swamp. This is the first 

 record of it having been found in Canada. This shell must not be confounded 

 with Amnicola Cincinnalensis, Anthony. 



