152 Mr. A. Hancock^s Notes on Buccinum undatum. 



is strong, rather rough and without an epidermis, but on mud 

 it is clothed with a thick hairy epidermis, and is comparatively 

 smooth and thin. No doubt many causes are in operation to 

 produce these changes, and the stillness or the agitation of the 

 water may have some influence ; but the nature of the ground 

 and depth would appear to be the chief agents in modifying the 

 forms of this species. 



The mouth of B. undatum is oval, and the arch of the colu- 

 mella is not much interrupted at its junction with the outer lip 

 by the bulging of the body whorl into the mouth ; near the mid- 

 dle there is an obscure fold or swelling which gives to the colu- 

 mella the appearance of being twice bent, and before sloping off 

 to the left it is advanced towards the outer lip : the enamel does 

 not extend far over the body whorl. 



Slight variations of course occur ; in some the mouth is wider 

 and more rounded than in others, and the columella varies a little 

 in length : as a general rule it is shortest in the thin and delicate 

 varieties, but to this there are many exceptions. 



All the various forms of B. undatum concur in these characters 

 of the columella and mouth, and may be placed with one or other 

 of the three principal varieties found on the coast of Northumber- 

 land, which I shall now proceed to describe. 



Variety 1. is found in forty fathoms water and upwards on a 

 muddy bottom. 



Mr. Alder informs me that on the west coast of Scotland it 

 occurs in much shallower water. 



This variety is undoubtedly the true B. undatum^ and is taken 

 everywhere on the British shores: it is sometimes four or five 

 inches long ; the shell is moderately thick with the undulations 

 well-developed, and is always covered with a somewhat strong 

 hairy epidermis ; the spire is usually as long as the mouth, and 

 the whorls are considerably rounded. In this state it is the 

 B. vulgare of Da Costa, and the jB. undatum of Miiller, Bi-uguiere, 

 Montagu, Donovan, Kiener, Brown and others. The B. angli- 

 canum of Brown and the B. striatum of Pennant also belong to 

 this state, varying only by having the undulations more or less 

 obliterated, and the spiral striae well-marked and regular. The 

 B. anglicanum of Lamarck is not a British species. 



This variety is occasionally very thin and delicate, and has the 

 spire sometimes considerably produced and the whorls much 

 rounded. The B. undatum of Brown (Illust. Conch. 2nd. ed. pi. 3. 

 fig. 2) is an example of the extreme form of this state which oc- 

 curs not unfrequently on the Dogger-bank. It is however impos- 

 sible to draw any line of demarcation between these thin, delicate, 

 elongated shells and the more general appearance of this variety. 



Fleming unites B, Humphrey sianum with his B. striatum. I 



