TOMLIN AND MARQUAND : SHELLS OF THK CHANNEL ISLANDS. 2iig 



Guernsey, rather common at Clarence Battery, at Cobo, and near St. 

 Andrew's Church. 



H. revelata Mich. — Occurs in all the islands. In Guernsey, 

 locally common on the cliffs, and also at Cobo. Rather frequent on 

 the cliffs in Alderney. This species is best collected in dry weather, 

 when it may be found at the foot of rocks that are closely edged with 

 short thick grass and other vegetation ; in wet weather it promenades 

 freely, and from its colour is not very easy to detect. 



H. pisana Miill. — Jersey, in St. Clement's Bay. Guernsey, ex- 

 tremely abundant and fine all round Vazon Bay, and in a less degree 

 at Bordeaux Harbour. Does not occur in the other islands. The 

 history of the introduction of this species into Guernsey has been told 

 in detail by Dr. Lukis (y. Conch., vol. 2, pp. 332-3), the evidence of 

 his daughter, Mrs. CoUings, decisively settling the question. The two 

 localities in Guernsey produce very different forms : In the western 

 habitat at Vazon, the shells are thick, strong, and well coloured) 

 similar to those found at Tenby ; whereas, on the eastern shore, at 

 Bordeaux, they are much thinner and lighter coloured, with a con- 

 siderable percentage of white ones. 



Var. albida Moq. — Bordeaux Harbour and Vale Castle, 

 Guernsey. 



Var. minor Bourg. — Vazon, Guernsey, with the type. Average 

 diameter, 15 mm., but we have found a perfectly-formed specimen 

 measuring only 13 mm. 



H. virgata DaCosta. — Abundant in all the islands, except Sark, 

 where it appears to be confined to the hill above the harbour. On 

 sandy fiats by the sea the shells almost always belong to the small, 

 conical form {siibniaritimd). A young sinistral specimen was found 

 alive at St. Sampson's, Guernse}', in 1891 {J. Couch., vol. 7, p. 44). 



Var. subtnaritima Desm. — Equally ubiquitous, and presenting 

 most of the colour-variations of the type. 



Var. fasciata Moq.— Abundant. This is what we usually con- 

 sider the type. 



Var. subalbida Poir. — Very common. 



Var. albicans Grat. — Also very common. 



Var. leucozona Tayl. — Common, but rather more local than the 

 preceding. Abundant in Alderney. The prevailing colour is some- 

 times light-brown, instead of blackish; and in Alderney a form is not 

 infrequent in which the white band is very slender or even altogether 

 wanting, so that the shells, if found apart from connecting links, would 

 certainly be ascribed to the var. nigrescens Grat. 



Var. rufula Moq. — Reddish-yellow shells are locally common in 

 Guernsey, which seem referable to this variety. 



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