The Canadian Field-Naturalist 



[Vol. XXXVI. 



difiFerent in shape, having the superior margin 

 more curved and the beaks narrower and more 

 elevated. The types are from Hess Lake, Mich., 

 but the species has a wide distribution from New 

 England to Pennsylvania and Minnesota. It is 

 described as having resemblance to small forms of 

 splendidulum. The hinge is markedly strong and 

 like that of variabile and compressum. 



40. PisiDiUM ABDITUM Haldeman. Many forms 

 now regarded as distinct were formerly thought to 

 belong to this species. Dr. Sterki examined the 

 authentic specimens, seven in number, from the 

 Temple Prime collection. He states (Nautilus, 

 XXVI, 6) that the description in Prime's Mono- 

 graph of the CorbicuHdea is quite inadequate 

 even with respect to the form of the shells assumed 

 to be the types, and that there are several geo- 

 graphical subspecies. I have found what Dr. 

 Sterki regards as true abditum in Dow's Swamp 

 and in a pond near Casselman. Heron does not, I 

 think, give the locahty in which he found the 

 shells doutbfully assigned to this species. 



41. PisiDiUM SPHAERICUM Sterki. Among a lot 

 of shells collected at the extreme end of Gore Bay 

 in the Manitoulin Islands was an almost globular 

 pisidium which Dr. Sterki recognized as identical 

 with a species known to occur from Maine to 

 Virginia and long confounded with abditum. He 

 described it in The Nautilus, XXIV, 8. It is 

 stated to be easily distinguishable from larger 

 forms of abditum by the large and prominent 

 beaks situated close to the posterior end of the 

 mussel, and the strong hinge. Average propor- 

 tions are 100; 90; 76. My shells are allless than 

 5 mm. in length. 



42. Pisidium adamsi (Prime) affine Sterki. 

 When Dr. Sterki described P. affine (1901) (Nau- 

 tilus, XV, 66), he had seen no specimen of adamsi, 

 and from the description of the latter species 

 considered that the two were distinct. After 

 examining the specimen of adamsi in the Prime 



collection he concluded that the two were speci- 

 fically identical. The only affine I have found 

 were procured in the large pond on the Metro- 

 politan Electric Company's property, south of the 

 Des Chenes Rapids. 



43. Pisidium noveboracense Prime. A way- 

 side ditch between the third and fourth concession 

 of Nepean, east of Fallowfield, was found to con- 

 tain this shell in large numbers. It doubtless 

 occurs in many other localities. Several varieties 

 have been described by Dr. Sterki. The more 

 typical form is thought to be that which is found 

 in spring brooks. 



44. Pisidium elevatum Sterki. A streamlet 

 formed by the overflow from springs in the Bell 

 gravel pit near Britannia at one time afforded 

 many examples of this shell. None could be 

 found in the summer of 1921 perhaps owing to 

 a lack of diligence on the part of the seeker after 

 specimens. Dr. Sterki was disposed at first to 

 consider the shells a variety of noveboracense, but 

 in his catalogue lists it as distinct. I have found 

 it only in the locality mentioned. 



45. Pisidium subrotundum Sterki. Though 

 but recently recognized as distinct, this shell was 

 long unnamed or doubtfully referred to other 

 species. It has a v/ide distribution in Canada, 

 being found from Jupiter River, Anticosti, to the 

 Albany and Attawapiscat rivers in north-western 

 Ontario, where it was found by Mr. Mclnnes. 

 It is doubtless the unnamed pisidium from the 

 Attawapiscat river referred to in report of the 

 Bureau of Mines for 1912. 



Near Ottawa the shell has been found in Dow's 

 Swamp and in a spring on the Hare farm in 

 Nepean. On the north shore of Lake Huron near 

 Cutler a few specimens were obtained in a ditch 

 beside the railway, north of the Indian village of 

 Kashaboiwe. 



(To be concluded.) 



THE FRESH WATER LEECHES (HIRUDINEA) OF SOUTHERN CANADA 



By J. Percy Moore 



Hitherto little has been published relating to 

 the distribution of leeches in the Canadian Pro- 

 vinces and that little has been limited practically 

 to the Great Lake shores of the Province of 

 Ontario. The leech fauna of the latter region is 

 fairly well known, especially since the publication 

 of Miss Ryerson's paper on the extensive collec- 

 tions made in Georgian Bay under the auspices 

 of the Dominion Biological Station and of Toronto 

 University. This enumerates seventeen species 



in all. Twelve species, of which specimens were 

 actually taken on the Canadian shore of Lake 

 Erie, are listed in my own paper on the Hirudinea 

 and Oligochoeta of the Great Lakes region. 

 Earlier records from the Canadian side of the 

 Great Lakes are by Verrill and Nicholson. Baird 

 has described a single species from Vancouver and 

 one from Great Bear Lake and here and there in 

 the narratives of exploring expeditions and 

 travelers in Canada casual references to the 



