322 APPENDIX. 



Bulla conuloidea, S. Wood. 



The shell called B. conulus, S. Wood, 'Mon, Crag. Moll.,' part 1, p. 173, t. 21, fig. 2, is, I now believe, 

 distinct fiom the Paris Basin shell, to which I had assigned it. A better examination with more specimens, 

 some of which were obligingly forwarded to me by M. Dcshayes, have shown that although the two shells 

 are very closely allied, the dili'erences are such as to warrant a specific separation. 1 therefore propose the 

 above alteration for the Crag shell. The species from the Basin of the Adour, called by Grateloup, B. 

 conulus and B. anyistoma, which I had considered synonymous, I have been unable to examine whether 

 they be more nearly related to the Older Tertiary or to the Crag species. 



Bulla hydatis, Linn. 



This is enumerated in Mr. Dixon's ' List of the Upper Tertiary Fossils at Bracklesham.' 



Bulla ampulla. 



Mentioned in Sir R. Murchison's ' Silur. Syst.,' p. 53.J, as a Tertiary fossil, found at Kempsey, near 

 Worcester. I am unable to say whether these two be the same or different species. 



Bulla acuminata. S. Wood. Crag. Moll., vol. i, p. 171. 



In the Synoptical Table at the end of the first volume of the 'Crag Mollusca' is a x against this name in 

 the line of Eocene fossils, as if intended to denote the presence of the recent species, acuminata, during the 

 Period of the Older Tertiaries.* This is a misprint ; no mention is made of such existence in the text at the 

 above reference. An unfigured species has, however, been found at Barton, closely resembling the recent 

 shell in having a pointed or acuminated termination, with the spire enveloped, but the Older Tertiary fossil 

 is evidently distinct. 



Systematists appear to labour under great difficulties in the generic divisions of the Bullae, the form of 

 the shell appearing almost alone to determine the distinctions. Our little species rejoices iu the title of 

 several generic aliases. Prefessor Loven has removed it from Bulla into a proposed genus called Cylichna. 

 Messrs. Forbes and Hanley placed it (with a doubt) in Ovula. It was called Folvula by Adams ; and Mr. 

 Woodward has united it with Tornatina. A knowledge of the animal, when possessed, will assist in its true 

 assignment, and may possibly justify a different position ; but at present the shell alone is all we have to 

 guide us as to its true relations, and from this it appears to differ only as a species from Bulla cylindracea, 

 and other cylindrically convoluted shells, and whatever may be considered more essential distinctions for 

 generic separation iu such inflated species as Bulla ampulla, &r., the simple difference in this, at least from 

 the cylindrically formed shells, is merely a greater elevation of the outer lip, so as to conceal the turns of the 

 spire : or perhaps it would be more correct to speak of it as a prolongation of the outer lip into a pointed 

 termination for the excurrent canal, instead of being at the junction or suture of the volution ; an 

 approximation to this may be seen iu those species, such as B. umbilicatu, &c., in which the outer lip is 

 extended retreally or retreatingly, so as to cause a concavity where the spire is depressed but not 

 hidden. 



* This column contains also a few other crosses, intimating the supposed existence during the Eocene 

 Periods of those species against which they are attached. Since that table was published I have given to 

 them a more special examination, and although there are two or three (particularly the species of 

 Pleurotoma) that present many characters in common, there is not one therein included that can be 

 undoubtedly said to have lived during the joint Periods of the Older Tertiaries and the Crag. 



