THE NAUTILUS. 39 



fauna which formerly flourished in this region, will appear in 

 a forthcoming publication of the Boston Society of Natural 

 History. I therefore confine myself to the description of a 

 new mollusk which occurs quite plentifully in the material 

 submitted to me, referring those desiring further informa- 

 tion regarding its age and the species with which it was found 

 associated, to the publication mentioned above. 



VlTRINELLA SHIMERI, Sp. nOV. PL II, figS. 6, 7, 8. 



Shell small, white, solid, depressed, whorls three, the ulti- 

 mate rapidly enlarging; smooth above, beneath with about 

 eighteen deeply incised lines radiating from the umbilical re- 

 gion. Suture distinct, umbilicus small, deep, aperture very 

 oblique, circular, not modified by previous whorl, peritreme 

 not continuous, modified to a more or less thin glaze on body 

 whorl, outer lip simple, columellar lip greatly thickened in the 

 direction of and encroaching on the umbilical region. Great- 

 est diameter 1.25 mm., height .5 mm. 



It is most readily distinguished from other Vitrinellas, by 

 the radiating lines of the base, caused by the folding back of 

 the thickened inner lip at regular stages of growth. Viewed 

 from above the strongly curved continuation of the outer lip 

 from the suture to the periphery, is more noticeable than in 

 any related species. 



The genus Vitrinella has been restricted by Miss Katharine 

 J. Bush (Trans. Conn. Acad. Sci., vol. 10, 1897) to a group 

 of " small more or less hyaline " shells, etc. While V. shimeri 

 can not possibly be considered as hyaline it agrees well with 

 all of the other characters of the genus. It is possible that 

 its solid opaque appearance may be the result of the age 

 of the specimens. No species of Vitrinella have been pre- 

 viously recorded from New England. 



Associated with Nassa obsoleta, Mulinia lateralis, Odostomia 

 bisuturaUs, My a arenaria and Macoma balthica. V. shimeri 

 belonged to the " between tide" fauna of what were formerly 

 the Charles River flats. 



Type: Museum of Comparative Zoology, no. 2600. Para- 

 types: U. S. National Museum, Boston Society of Natural 



