2G3 

 REPORT OF THE CONCHOLOGICAL BRANCfT. 



To the Council of the Ottawa Field-Naturalists Clah : 



Gentlemen, — During the past year this section of the club has 

 made gratifying progress in the work assigned to it. In conjunction 

 ■with the botanical branch, three sub-excursions were held in the early 

 part of the season. The tirst, to the niarl beds east of Hemlock Lake, 

 aJBforded many of the commoner land shells, such as Mesodon albolahris, 

 Saj, Fatula alternata, Say, Patida strialella, Anth., Stenotrema 

 moiiodon, Rackett, and Succinea ohliqua, Say. Macrocylis concava, Say, 

 Ili/alina arborea, Say, //. viridala, Mke., and Conulus fulvus, Drap., 

 were obtained in less numbei's, together with two bleached s[)ecimens 

 of Mesodon sayii, Binney, and one of Zonites inornatus, Say. Both the 

 latter species i)robably lived in this locality within a very recent period. 

 It is not likely that they long survived the destruction of the forest 

 which once favoured them b}' equalizing the temperature, preventing 

 rapid evaporation and condensing at night generous sup[)lies of moist- 

 ure from the atmosphere. 



On the way homeward Campeloina decisum, Say, Limnaia desidwsa, 

 Say, and Planorhis campanidatus, Say, were collected in the lake. 

 Anodonta fluviatilis, Dillw., was observed in quantity in muskrat heaps 

 at the west end of the lake, but no perfect shells were found, one valve 

 being invariably broken. In one s])ecimen of the P. cainpanulatus, the 

 bell shaped mouth after being fully formed had contracted and con- 

 tinued growing for half a whorl, wiien another enlarged aperture was 

 formed. The result is /'. (Adula) multivolvis, Case, in every particular 

 but one. The shell from Hemlock 'Lake has only four and a half 

 whorls, instead of the" '-'seven whorls" of Case's somewhat mythical 

 species, which in fact seems to have been nothing more than P. canipa- 

 nulatus with the aperture duplicated. 



The next expedition was to Dow's Swamp. A lialt was made 

 ■en route at the Bank street bridge, where Valvata tricarinata, Say, 

 Limncea stacjnalis, L , Phijsa ancillaria, Say, Planorhis trivolvis, Stty, 

 and P. campanulatus were collected. Very fine specimens of L. stognalis 

 occur at many points along the RideAu Canal, but nowhere of more 

 graceful proportions and beautifal lustre than in the dead water ex- 



