OF NORTHUMBERLAND AND DURHAM. 55 



12. R. 1 DIAPHANA, Alder. 



Itissoa ? glabra, Aid. in Ann. Nat. Hist. xiii. 325, t. 8, f. 1-4. 



On sea-weeds in pools among the rocks at CuUercoats, rare. — 

 /. 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. Bailee, 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, i^ejMSsac, 



1. L. LiTTOREA, Linn, (common periwinkle.) 



Turbo liUoreics, 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. RUDis, Mato7i. 



Turbo rudis, Mont. Test. Brit. 304. 

 On rocks and in pools near high-water mark, common. Beau- 

 tifully banded varieties (L. zonata, BeanJ occur at Newbiggin 

 and Bamborough, as well as on some other parts of the coast. 



3. L. RUDissiMA, 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, 

 thtit we are unwilling to speak very decidedly concerning them. 

 The present, though very nearly resembling L. rudis, has the 

 shell always thinner and smaller, and is distinguished from the 

 young of that species by liaving the columella not so broad, nor 

 so much produced and angulated at the base. It has also the 

 spiral ridges generally very strong and conspicuous; but in this 



