KENNARD : ON SUBDIVISIONS OF PLAN0RBI8. 49 



is intermediate between parvus and arcticus, though how a species 

 which is spirally striate can be intermediate between two others 

 neither of which possesses this character is more than I can under- 

 stand. Dr. Lall also throws doubt on the specific name of Planorhis 

 alhus, Miiller. He says with reference to Planorhis hirsutus, Gould, ^ 

 "The identity of our American species with the so-called P. albus, 

 Miill., of Europe, I do not doubt, but whether the name albus is the 

 proper one to use for the latter is open to question, and on the present 

 occasion I prefer to use a name about whose application no doubt can 

 exist." 



With regard to the above statement, Dr. A. C. Johansen informed 

 me that Miiller's types are undoubtedly the species which is always 

 called by the name albus. 



It is possible, however, that Dr. Dall refers to the claim that has 

 been put forward that P. spirorbis, Linn., should be used instead of 

 P. albus, Miill., but any attempt to transfer a well-established name 

 such as spirorbis from the species to which it has been applied for 

 over one hundred years to another common species should, I think, be 

 resisted by all students, for endless confusion would result. Whether 

 P. albus,. Miill., and P. hirsutus, Gould, should be considered one 

 species is an old and vexed question. Personally I am convinced they 

 are distinct, and this opinion is, I believe, shared by many competent 

 malacologists. 



I must tender my best thanks to Dr. A. C. Johansen, Messrs. Bryant 

 Walker and A. Mayfield, and Dr. E. Wiist for kind assistance. 



Op. cit., p. 94. 



VOL. Vm. — MARCH, 1908. 



