OF NORTHUMRBRLAND AND DURHAM. 53 



Mr. Bean has distinguished it in his cabinet under the MS. name 

 of 0. costata. 



9. 0. OBLIQTTA, Alder. 



Odostomia? obliqua, Aid. in Ann. Nat. Hist. xiii. 327, t. 8, 

 f. 12. 

 In shell-sand, Tynemouth, rare. — J. A. 



[In the preceding family, to which we have not ventured to give 

 a name, we have brought together, provisionally, those genera 

 formerly considered to belong to the Tui-binidce, whose ani- 

 mals have a retractile proboscis. In the four following fami- 

 lies, the animals have the head more or less proboscidiform, 

 but there is no real proboscis.] 



Family. LiTTORiNiDiE, Gra?/. 



49. RISSOA, Freminvilh. 



1. R. COSTATA, Adams. 



Turho costatus, Mont. Test. Brit. 311, t. 10, f. 6. 



Bissoa exigua, Mich. Desc. du Rissoa, 18, f 29, 30. 

 In shell-sand, frequent. It has not been found alive here, but, 

 like most of the small species found in sand, it probably inhabits 

 the Laminarian zone beyond low-water mark. 



2. R. STRIATA, Adams. 



Turho striatus, Mont. Test. Brit. 312. 

 Rissoa minutissima, Mich. Desc. du Rissoa, 20, t. 27, 2S. 

 In pools among the rocks, frequent. This is one of the com- 

 monest of the shells thrown up in sand. 



Pyramis candidus and P. discors of Brown are apparently only 

 varieties of this very common and widely diffused species. 



3. R. PARVA, Da Costa. 



Turho parvus, Mont. Test, Brit. 310. 

 In shell-sand, common ; and alive beyond low-water mark. 

 This species is found alive, though sparingly, on small sea-weeds 

 among the rocks left bare by the tide. Its principal locality 

 appears to be beyond low-water mark, and a small variety, with 

 a thinner and more glossy shell, is not uncommon on corallines, 

 from about twenty fathoms water. 



