OF NORTHUMBERLAND AND DURHAM. 149 
12. R.? prapHana, Alder. 
Rissoa ? glabra, Ald.in Ann. Nat. Hist. xiii. 325, t. 8, f 1-4. 
On sea-weeds in pools among the rocks at Cullercoats, rare.— 
J. A. 
When this species was published in the Annals of Natural 
History, it was referred to the Rissoa glabra of Brown’s Illustra- 
tions, but, since that time, we have seen, through the favour of 
Mr. Barlee, an allied species from the south coast, that more 
nearly agrees with Captain Brown’s figure, and we have, there- 
fore, now given this the name of diaphana. It is not a true 
Rissoa, as we have already pointed out. The peculiar character 
of the animal requires that it should be raised to the rank of a 
genus. 
50. LITTORINA, Férussac. 
1. L. urrrorea, Zinn. (common periwinkle.) 
Turbo littoreus, Mont. Test. Brit. 301. 
In shallow pools and on stones within tide-marks, common, 
especially at and a little above half-tide level. A red variety is 
not uncommon on some parts of the coast. 
2. L. nupis, Maton. 
Turbo rudis, Mont. Test. Brit. 304. 
On rocks and in pools near high-water mark, common. Beau- 
tifully banded varieties (L. zonata, Bean) occur at Newbiggin 
and Bamborough, as well as on some other parts of the coast. 
3. L. Rupisstma, Bean. 
Littorina rudissima, Bean in Thorpe’s Brit. Mar. Conch. 266. 
On rocks, bare of sea-weed, at and a little above high-water 
mark, abundant ; frequently found in crevices on the face of a 
cliff. 
The species of this most difficult genus are so extremely varia- 
ble, and approach each other so closely in the different varieties, 
that we are unwilling to speak very decidedly concerning them. 
The present, though very nearly resembling Z. rudis, has the 
shell always thinner and smaller, and is distinguished from the 
young of that species by having the columella not go broad, nor 
so much produced and angulated at the base. It has also the 
spiral ridges generally very strong and conspicuous; but in this 
