THE NAUTILUS. 41 



Holospira bilamellata Dall. PI. V, figs. 8, 9. 



Hacheta Grande Mts., New Mex., 1910. 



This shell was normal up to the penultimate whorl, when without 

 any apparent injury it contracts suddenly to three-fifths the former 

 diameter. The last whorl enlarges again somewhat, and is nearly 

 normal. A normal example is figured for comparison, fig. 9. 



Holospira n. sp. 



Dragoon Mts., Arizona, 1910. 



A strongly ribbed new species which will shortly be described by 

 Messrs. Pilsbry and Ferriss. The shell was broken at the end of 

 the eighth whorl. The next 2^ whorls are ribless ; ribs then begin 

 again irregularly, finally becoming normal on the last whorl. 



Oreohelix strigosa depressa (Ckll) PI. V, fig. 16. 



Jacob's Canyon, Kaibab Mts., Ariz., 1910. 



A scalariform specimen, the last whorl free in front. There are 

 no signs of this shell ever having been injured in the least. Normal 

 shells are shown in tigs. 18, 19. 



A reversed specimen from Powell Plateau, Grand Canyon, Ariz., 

 1909 is shown in fig. 17. J. H. Ferriss of Joliet, Ills., has a similar 

 one. 



Planorbis bicarinatus Say. PI. V, fig. 4. 



Lily Lake, La Porte, Ind., 1909. 



This extraordinary specimen has the general shape of Viviparus 

 intertextus with a small umbilicus and a deeply channeled suture. 

 The aperture is oval with expanded peristome. So abnormal in 

 shape is this specimen that it takes some study to see the common 

 Planorbis bicarinatus in it. 



Campeloma decisum (Say). 



Pine Lake, La Porte, Ind., 1906. 



While reversed specimens of Campeloma are not rare the novelty 

 of this one is that it contained three young, all of which are reversed. 



NOTE BT THE EDITOR. Little has been published upon abnormal 

 shells in this country, though there must be abundant material scat- 

 tered among collections. The notes given above afford suggestions 

 for a classification of teratologic shells into several classes as follows : 

 1. Shells in which growth has been resumed after the completion of 

 a normal peristome, figures 5 and 12. 



