4 THE NAUTILUS. 



able habitats, and is, for that reason, restricted to the unfavorable, 

 sparsely populated, boreal bog, just as the boreal plants and animals 

 are confined to these relict islands throughout the transition and the 

 northern parts of the Upper Austral zones. These rivals would 

 probably not be other shells in the case under consideration, as Cir- 

 cinaria is the only snail in the region that is mainly carnivorous in 

 habits, but would probably be some of the carnivorous arthropods. 



The shells themselves show the influence of poor conditions as 

 they are, thin, fragile, and dwarfed. The largest specimen collected, 

 which was a shell of four and one-half whorls measures : greater 

 diameter 11.9 mm., lesser diameter 10.4 mm., altitude 5.3 mm., 

 while a shell with five whorls from southern Michigan measures : 

 18.9 mm., 16 mm., 8.5 mm. ; and a young shell of four and one-half 

 whorls from the same region as the latter : 13.9 mm., 11.8 mm., 6.4 

 mm. This difference in size is even more marked in the embryonic 

 first whorl, and the northern shells are more transparent and vitreous 

 than the southern, have little of the latter's clouded, milky appear- 

 ance, and truly resemble in texture an over-grown Vitrea. In addi- 

 tion, the revolving, microscopic wrinkles, which mark the typical 

 shells over the entire upper surface but most strongly along the 

 inner, sutural slope of each whorl, are more delicately and strongly 

 marked in the northern form. 



The question as to how this form got into this region is, at present, 

 unanswerable, but the fact that the bog, in which it was found, lies 

 between the Nipissing fossil beach and the present shore of Burt 

 Lake is at least interesting in this connection. 



BTJMINA DECOLLATA IN MOBILE AND NEW OBLEANS. 



BT. HERBERT H. SMITH. 



This species is common in Southern Europe and has been carried 

 by commerce to Bermuda, Havana and other places. As far as I 

 know, the only recorded North American locality is Charleston, 

 S. C., where it has been fully naturalized for many years. For its 

 discovery in Mobile and New Orleans we are indebted to Mr. L. H. 

 McNeill, of the former city. This gentleman sent to me a drawing 

 of the shell, stating that he had first noticed it in New Orleans as 



