The Canadian Field-Naturalist 



[Vol. XXXVI 



with a burst of speed that soon takes them out of 

 shot-gun range. It is usually impossible to 

 approach within range when they are feeding in 

 the open, neither will they allow a close approach 

 when they are in the perching trees. When 

 pigeon-shooting was legal, a common practice of 

 the hunter was to hide under a favorite perching 

 tree and shoot the birds as they alighted. Many 

 of these trees were dead giants, their tops high 

 above the green timber, and as pigeons usually 

 chose to settle on the topmost branches, the 

 shooting was done chiefly with a 22 calibre rifie. 



Sometimes good shooting was had by the use of a 

 blind and dead birds for decoys, and in some 

 places the conditions were suitable for flight shoot- 

 ing. No matter how they were hunted a good 

 bag tested the resources of the hunter. That this 

 fine game bird will be preserved for future genera- 

 tions of sportsmen is indicated by their pheno- 

 menal increase during the past four years and 

 incidentally this furnishes proof that the inter- 

 national protection of Migratory Birds is entirely 

 effective. 



CANADIAN SPHAERIIDAE. 



By The Hon. Mr. Justice Latchford. 



{Continued from Vol. XXXV, p. 70) 



PiSIDIUM 



In 1821 Carl Pfeiffer established this genus to 

 designate a group of the Cycladidae, as the Sphae- 

 Hidae were then called, which had but a single 

 siphonal tube, and that, as he thought, at the 

 anterior end of the shell. The syphon, however, 

 projects from the end of the shell which is opposite 

 to that from which the foot is protruded. Pfeiffer's 

 error is due to the fact that the shell itself is 

 shorter behind than in front of the beaks a 

 character which with the single siphonal tube 

 distinguishes Pisidium from Sphaerium and 

 Musculium. 



The genus abounds throughout Canada. It 

 occurs in great numbers in almost every pond and 

 in the quieter waters of many of our lakes and 

 rivers. From the clear cold streams in the 

 Laurentian Hills it is usually absent, but it is 

 found in every brook and ditch on the south side 

 of Ottawa. The shells must be sought by sifting. 

 They are invariably sunk in the sand or mud, 

 and certain forms inhabit very deep water. 

 As some do not exceed a millimeter or two in 

 diameter a dredge with a very fine mesh should be 

 used by the collector. 



The Pisidia present exceptional difficulties in 

 identification. The soft parts of species differing 

 widely in external appearance are so similar that 

 they have up to the present afforded no charac- 

 ters of value to the diagnostician. Externally the 

 form or size of the same species is sometimes 

 modified by varying conditions. The characters 

 mainly relied on by systematists are those pre- 

 sented by the hinge teeth, which are complicated 

 in structure and arrangement. They are fairly 

 constant in any one species and different in every 

 Other species. It is on the details of the hinge 



that Mr. B. B. Woodward particularly relies in 

 his monograph on the British and Irish Pisidia in 

 the British Museum. (Catalogue of Species of 

 Pisidium, Longman's, 1913.) His method is too 

 technical to be more than mentioned here. Apply- 

 ing it with great labour and the utmost precision 

 to the vast collections available to him he has 

 reduced the number of species found in Great 

 Britain and Ireland to seventeen, three of which 

 are known only as fossils. His monograph with 

 its thousands of figures is a monument to his 

 industry and skill. 



When the hinge teeth are considered in connec- 

 tion with external characteristics they seem to 

 afford the best means of distinguishing one species 

 from another. Yet so great are the difficulties 

 presented in identifying all but a few of the genus 

 found in Canada that I have been constrained to 

 rely almost wholly on the judgment of Dr. Victor 

 Sterki of New Philadelphia, Ohio, who has made 

 these shells the subject of intensive study. He 

 has accumulated material in vast quantities from 

 all over the continent, and examined the collec- 

 tions in the National and other United States 

 Museums, including what are supposed to be the 

 type specimens of the earlier writers. In his 

 Preliminary Catalogue, to which I have frequently 

 referred in previous papers, he enumerates no less 

 than one hundred and thirty species and varieties 

 from Canada and the United States. In his 

 monograph of the Pisidia on which he is now 

 engaged there will doubtless be modifications of 

 this list. In the meantime I follow it, and all 

 identifications of shells which I have collected are 

 given upon his high authority. His descriptions 

 of new species are repeated with his permission. 



But few shells of the genus were collected in the 

 early years of the Club's activities. Heron's list 



