Zoological Society. 



PROCEEDINGS OF LEARNED SOCIETIES. 



ZOOLOGICAL SOCIETY. 

 March 24, 1863.— W. H. Flower, Esq., F.Z.S., in the Chair. 



Notes on Two New Species of Mammals. By J. K. Lord, 

 F.Z.S., Naturalist to the British North-American 

 Boundary Commission. 



My principal reason for bringing to your notice this evening two 

 animals, a Musk Rat and a Lagomys, that I propose making new 

 species, is to elicit from the zoologists who are before me opinions 

 on that most debatable of all debatable questions. Where does well- 

 marked variety end, and species begin ? Is it enough if you have 

 decided differences of habit, size, colour, and locaUty — variations 

 that are always constant, but without well-defined structural differ- 

 ences, or these, if any, but trivial in character ; or must there of ne- 

 cessity be decidedly marked variations in structure, particularly in 

 the sicull and dental formulae, as well as in habit, colour, size, and 

 habitat, to constitute a species ? I now have on the table four ani- 

 mals, two of which are described and figured, and two I believe 

 specifically distinct from the former ; and although the latter, as I 

 shall be able to point out to you, present differences of habit most 

 singularly well marked, and strongly defined differences of size and 

 colour, habitat, and range, yet an examination of their skulls shows 

 only some slight differences, principally in size. 



First, then, of the Musk Rat. The one which I believe is the well- 

 known Fiber zibethicus (Cuv.) makes its holes in the clayey banks 

 of streams and pools where the water runs slowly. The entrance is 

 always below the surface of the water ; the hole is dug up in a 

 slanting direction till above the water-level. A stage or flat place is 

 then cleared, which constitutes his dining-, drawing-, and bed-rooms ; 

 leading to the entrance of his mansion are a large number of open 

 cuttings, running in all directions, cut or dug in the mud at the bot- 

 tom of the water. When foraging about, as he usually does about 

 twilight, if alarmed, he dives at once into one of these cuttings, and, 

 rushing rapidly through it, stirs up the mud, and so fouling the 

 water, completely and effectually conceals himself. 



The other Musk Rat, which I propose to make a new species, and 

 to call Fiber osoyoosensis, having obtained it at a large lake (Lake 

 Osoyoos) situated between the Cascades and Rocky Mountains, and 

 through which the boundary -line (the 49th parallel of latitude) runs, 

 differs in size, in colour, in locality, but particularly in habits, from 

 the preceding. 



This fellow chooses as his haunt a clear pond or lake, and in water 

 from 3 to 4 feet deep constructs a house of bullrushes, in form 

 conical, built up from the bottom — how, I am at a loss to imagine, — 

 the roof cleverly arched over into a domed shape, and raised about 

 a foot above the watier. Up in this dome, skilfully constructed, is 

 his suite of apartments, the entrance to which is far below the sur- 



