BEL A. 217 



B. DECUSSATA, Couthouy. PL 29, figs. 55, 60, 65, 69 ; PL 27, figs. 

 21, 25 ; PL 28, figs. 35, 36 ; PL 30, fig. 94. 



Shell ovate-fusiform, with a moderate, scarcely turreted spire; 

 whorls six or seven, round-shouldered ; with about 24 sigmoid 

 longitudinal ribs, evanescing about the middle of the body-whorl, 

 close revolving striae cross the ribs ; sinus well marked, close to 

 the suture ; canal narrowed, but short ; columella nearly straight 

 in the middle ; color white, yellowish or pinkish white. 



Length, 9 mill. 



New England, northwards ; Labrador ; 



Greenland; Nova Zembla. 



This is B. scalaris (Yahl) of Reeve (PL 27, fig. 21) afterwards 

 changed to B. borealis. B. leucostoma, Reeve (PL 27, fig. 25), 

 B. reticulata, Yahl, according to Reeve. 



B. tenuicostata, M. Sars (PL 28, figs. 35, 36), differs only in 

 being smaller, with more numerous ribs. Verrill also describes 

 a var. pusilla, having the ribs less prominent and not so much 

 bent at the shoulder, giving the shell a smoother appearance. 

 Another variety is B. viridula, Moller not of Reeve, and of 

 which B. Kobelti, Yerkruzen (PL 30, fig. 94), is a synonym; 

 it is more strongly ribbed with a better defined shoulder 

 than the type, the ribs straighter. B. incisula, Yerrill (PL 29, 

 fig. 65), appears to me to be no more than a stunted, shouldered 

 variety, with straight ribs, approaching B. Kobelti. B. hebes, Yer- 

 rill (PL 29, fig. 69). and B. pygmsea, Yerrill (PL 29, fig. 60), are 

 also varietal forms, having slight distinctive characters, which 

 will appear by comparing the figures ; the latter is evidently from 

 its small size and fewer whorls a young specimen. B. Trevelyana, 

 var. Smithii, Jeffreys, is considered by Yerrill a doubtful variety 

 of his B. incisula. 



B. PINGELII, Moller. PL 29, fig. 64. 



Shell slender, with elongated spire, and moderately convex 

 whorls, with numerous longitudinal, rather straight ribs, excurved 

 above, and strong, elevated spiral lines, forming nodules where 

 they cross the ribs ; pale chestnut-brown, with the canal and 

 columella whitish. Length, 11-12 mill. 



Maine; Greenland; Norway. 



Not unfrequently confounded by authors with the next species, 



