THE NAUTILUS. 117 



Baker in his admirable " Lymnaeidae of North and Middle 

 America" (Chicago Academy of Sciences Pub. No. 3, 1911) 

 p. 120. Whereas the older classifications considered shell 

 characters alone, this author "proposed to classify the Lym- 

 nreids by the characters of the shell, genitalia (shape of pros- 

 tate, relative size and form of the penis and penis-sac) and 

 radula. ' ' 



On a basis of these criteria he has split the genus Lymnsea as 

 defined by Haldeman 1840, Gould, Binney 1868, Dall 1871, 

 Tryon 1872 & 1884 and more recently by Dall in 1905, into six 

 genera: Lymneea^ Pseudosuccinea, Radix, Bulimntfct, Acella and 

 Galba. He has done this mainly by raising a number of sub- 

 genera and sections of former authors to generic rank. I wish 

 to ask this question : Is this at the present time justifiable ? 

 (1) Baker lists 103 species arid varieties of the old Lymntza in 

 this work. Of but 33 have anything of the anatomy, radula and 

 genital organs been studied. Therefore the shell characteristics 

 are the important ones after all. (2) All these new genera are 

 based largely on quantitative characters. The only qualitative 

 character mentioned is the radula and this is given quite a sub- 

 ordinate place in the classification. (3) In his diagnosis of the 

 genus Galba in his key he states that the " Penis (epiphallus) is 

 shorter than the penis-sac" (Penis). 1 



However, for two of the species of this genus the epiphallus is 

 longer than the penis. See Baker p. 263 and 277. 



In the mind of the writer our present knowledge will not al- 

 low us to make a comprehensive classification of the Lymnseids 

 based on the anatomy of the snail. We know too few species 

 well. On the other hand the shell characters alone in a mollusk 

 with such a generalized form of shell as have the Lymnseids 

 are not characters on which one can base much reliance. 



On account of these reasons the writer would make the rec- 

 ommendation that the old genus Lymncea should be retained in 

 the sense that it has been used for the past seventy years. These 



1 1 am indebted to Dr. H. A. Pilsbry for calling my attention to the fact that 

 Baker has called the e/ iphalins the penis, and the true penis he has called the 

 penis-sac. In this paper I will adhere to the general usage and refer to the epi- 

 phallus and penis instead of penis and penis-sac. 



