RISSOA. 



TESTA iinivalvis, libera, oblonga vel turrita, 

 acuminata, parva, apertura suborbiculari, In- 

 tegra, superne subacuminata, infra subefFusa, 

 peritremate incrassato non reflexo, prope colu- 

 mellse basin subemarginato. Operculum cor- 

 neum. 



A Genus consisting entirely, as far as we know of minute 

 shells, the largest of which does not exceed an inch in 

 length, and very few of which attain to half that size. 

 It appears to us to be most nearly related to Scalaria from 

 which it differs principally in the peritreme not being 

 reflected. There are many species, which vary from an 

 oblong, to an acuminated turrited form. All we have 

 met with are littoral shells, and several species abound 

 on our own shores. We do not remember to have ever 

 met with any fossil species. 



Shell univalve, free, oblong or turrited, acuminated, 

 small, with a nearly orbicular, entire aperture, which is 

 somewhat acuminated at its upper part and slightly effuse 

 at the lower, peritreme thickened, not reflected, with a 

 slight notch at the base of the columella. Operculum 

 horny. 



We have given representations of four species. 



