THE NAUTILUS. 21 



In the first part of this paper (anatomical and systematic) the 

 author describes the anatomy, radula and genitalia of Lymnsea 

 stagnalis, Radix auricularia and ovata, and Galba palustris. It is 

 apparent that there is great variability in the radula of many of 

 the species of Lymnasids. In the paper in question, auricularia 

 is described and figured with both bicuspid and tricuspid lat- 

 erals, the first lateral being invariably tricuspid. In the indi- 

 viduals of the American form (introduced) which have been 

 examined, the first lateral w y as always tricuspid, but the bal- 

 ance were bicuspid or with a small entoconic swelling. Palustris 

 in Roszkowski's paper has both bicuspid and tricuspid laterals, 

 while in the American form examined the laterals have in all 

 cases been bicuspid. This is true also of reflexa, emarginata, 

 catascopium and others of this group. As remarked elsewhere, 

 the writer has not been able to observe a normal central tooth 

 of LymnaBa which was other than unicuspid, though several 

 pathological examples have been seen in which there were one 

 or more side cusps. Very high powers have been used and 

 great care has been exercised in making examinations. 



In order to verify the form of teeth of American Lymnaeas 

 published by the writer, several species, among them palustris, 

 reflexa, mighelsi, danielsi, stagnalis, auricularia, obrussa, and col- 

 umella, were reexamined, and no deviation from the published 

 figures was observed. All of the lateral teeth of the palustris 

 group were bicuspid. Stagnalis has a slight endoconic swelling 

 which might be taken for a typical cusp. If the difference 

 pointed out by Roszkowski for both stagnalis and palustris would 

 prove stable there might be grounds for separating the European 

 and American species, in which cases the latter species would 

 become appressa Say and nuttalliana Lea. In auricularia the lat- 

 eral teeth vary as shown by Roszkowski (plate 16, figs. 183-186) 

 being, according to this author normally tricuspid though some- 

 times with the first lateral tricuspid and the balance bicuspid, 

 as figured by the present writer. Upon reexamination, the 

 laterals of the Lincoln Park specimens were found to be as 

 figured by the writer and by Roszkowski on plate 16 figure 183. 



Additional comparative studies are needed in which many 

 individual radulae are observed to ascertain the amount of var- 



