134 THE NAUTILUS. 



ADDITIONAL NOTES ON BIFIDAKIA PENTODON AND B. TAPPANIANA. 



BY V. STERKI. 



We are indebted to Messrs. Vanatta and Pilsbry for their expose 

 of these species and their forms, in the March Nautilus. The es- 

 sence of it is that what we called B. pentodon Say is really tappani- 

 ana Ad., and the forms ranged under curvidens are pentodon Say. 



After once more looking over part of my materials 1 and the crit- 

 ical forms, I find occasion for a few notes which it may be permitted 

 to add. 



The form curta does not belong to pentodon, 7 but to tappaniana. 

 In some places it has almost the significance of a variety. The 

 shells of pentodon from wet situations are usually also more ventri- 

 cose, ovoid, than those from more elevated and comparatively dry 

 stations. 



Fresh, good shells of pentodon from many places are glassy, trans- 

 parent, colorless, while others are of a horny or milky hue ; those of 

 tappaniana are more generally so. B. pentodon from some places 

 has no callus or a very slight one in the palate. 



The " parietal " lamella in both species and all forms is really 

 composite,' i. e., composed of the parietal and angular, although the 

 latter is generally quite small, a mere appendage of the former, 

 especially in tappaniana, while in many specimens of pentodon it is 

 quite distinct, and in some the whole lamella is even bifid, somewhat 

 like that of B. hohingeri. 



The habits of the two species are rather different, and they are not 

 often found associated. Thus B. pentodon is common among moss 

 and grass in forest and on open slopes, even steep, stony and rocky 

 hillsides, where tappaniana is hardly ever found. The latter is prev- 

 alent in low, damp places, under wood, etc. 



One feature of interest may be mentioned here. Like those of 



1 About 250 entries on the two species. 



s The names in the following are used in the sense of Vanatta and Pilsbry in 

 the article referred to. 



3 Conf. Pilsbry and Vanatta, A Partial Revision of the Pupae of the United 

 States, Proc. Acad. Nat. Sc, Phila., 1900, p. 593, key ( Vertigoptis). Iu some 

 figures on the plates VI and VII in the Nautilus, the angular is shown, e. g., 

 Figs. 3, 12, 21, 27, 32. 



