Mr. K. A\'aller on a iiew British Species o/Rissoa. 137 



H'horU 5-6, sloping from the suture to the second ridge, and 

 well rounded thence to the lower suture ; the last whorl 

 exceeding half the length of the shell, and obliquely 

 rounded at the base. 



Sculpture : on the penultimate whorl four rather slender but 

 well-defined spiral ridges, the lower three of which arc 

 stronger than the highest one, which is on the upper slope 

 of the whorl. The ridges are crossed by about twenty- 

 eight perpendicular ribs, not so much elevated nor nearly 

 80 strong as the ridges, and forming with them square 

 cancellations, the intersections of the ridges and ribs being 

 scarcely raised, but slightly nodulous. The apical whorls 

 are marked with spiral rows of close angular punctures. 

 In each succeeding row the punctures lie below the ridges 

 separating those of the preceding row. The base of the 

 lowest whorl has 5-7 spiral ridges, for the most part un- 

 crossed by the ribs, which generally terminate at the lino 

 of the upper part of the mouth. 



Suture dcejSlv defined and somewhat excavated. 



Mouth roundish oval. 



Outer lip smooth inside, and strengthened outside by a broad 

 and strong rib. 



Inner Up smooth and rcticcu-d ou the pillar, making the peri- 

 stome continuous. 



Umbilical chink very small. 



Length 010 inch, breadth 0*07 inch. 



Its nearest ally is Rissoa cimieoides, Forbes {Rissoa sculptu of 

 F. & H., but not of Philippi) ; but it differs from that species 

 in being of smaller size and of thinner texture, in having the 

 whorls more rounded and with a rapid slope from the deep 

 suture to the second rib. The general outline is decidedly less 

 conical ; and while the longitudinal ribs are much the stronger 

 in R. cimieoides, the transverse ones are stronger in R. Jeffrej/si, 

 and the nodules at the intersections are much larger in the 

 former than in the latter shell. In the present species the 

 sculpture is infinitely more delicate than in its ally. The throat 

 is crenulated in R. cimieoides, but smooth in R. Jeffrei/si. R, 

 cimieoides is yellow, with purplish-brown blotches ; R. Jeffreysi 

 is porcelain-white. 



Its habitat is in sandy ground, in from 80 to 85 fathoms ; 

 and it has been taken in two localities at about eight miles and 

 thirty miles from Unst, the most northern of the Shetland 

 Islands. 



Mr. Jeffreys informs me that, when in Scandinavia, last year, 

 he saw two or three specimens in the Museum at Upsala, col- 



