304 APPENDIX. 



GASTEROPODA. 



The following land and fresh-water shells are from the Formations belonging to the Uppermost or 

 Newest Tertiaries of Great Britain. These shells are all, with the exception of four, undoubtedly identical 

 with species still in existence in England, and it is thought an insertion of their names alone, with a 

 reference to where thej' have been recently well figured and described, will be sufficient. The exceptions, 

 though here extinct, are still existing in other parts of Europe ; and as they were formerly inhabitants of 

 where their remains are now found, they claim a place in the Monograph of the Upper Tertiaries of the 

 British Isles. 



I am indebted to Jlr. John Brown, of Stanway, for the list of species from Copford and from Fisherton. 



latm and other decollated, or rather decapitated, shells, which appeared to have become so from the want 

 of the necessary connection between the shell and the more vital parts. It is to Dr. Fleming, perhaps, 

 that the real priority of the idea should be awarded. In his ' Philosophy of Zoology ' there is a very 

 .significant passage, where he speaks of the vitality of the shell when in intimate contact with the fluids of 

 the animal, foreshadowing there the belief, now generally entertained, that the calcareous portions of the 

 MoUusca are far from being inert matter, secreted merely as protective coverings to the softer parts (a 

 considerable section being wholly destitute of such coverings), but that they are truly constituent and 

 integral portions of the animals themselves, only with a larger amount of inorganic elements. 



It is well known that, in some of the extinct species of Ccphalopods, the tube is protected throughout 

 its entire length by n rigid, continuous, and inflexible covering, and one can scarcely refrain from an 

 expression of astonishment that naturalists, who have purposely studied, and largely published their views 

 upon the yautiliis and its congeners, should not have discerned the now presumed use of the siphuncle. 

 If seen, it is perhaps still more extraordinary that this silver cord should have had with it so little 

 explanation. 



My friend Mr. Edwards has (I think wisely) left the determination of the claim to priority to the 

 judgment of the members ; but an ulterior question arises, which is, whether the paragraph quoted by 

 Mr. Edwards in his address amounts to more than the suggestive passage by Dr. Fleming, similar in its 

 purport, to which I have referred. 



The two passages are here subjoined : — 



"The shell cannot be considered as dead matter so long as it remains in connection with the living 

 animal. In those animals in which the shell is external, there are muscles which connect the animal with 

 its external surface, and the bond of union being a substance soluble in water, the muscles can be detached 

 by maceration. The analogy between shell and bone is here obvious, although in the one case the con- 

 nection between the muscle and the bone is permanent, in the other between the muscle and the shell 

 temporary, or frequently changed during the life of the animal. But the vitality of the shell, if I may use 

 the expression, is demonstrated from the changes which it undergoes when detached from the animal. The 

 plates of animal matter harden, the epidermis dries, cracks, and falls ofl', and in many cases the colours 

 fade or disappear. We confess ourselves unable to point out the means employed by the animal to prevent 

 these changes from taking place by any process similar to circulation." — Phil, of Zool., by Dr. Fleming, 

 vol. ii, p. 405, 1822. 



"Whatever additional advantage the existing Nautilus might derive by the continuation of a vascular, 

 organized membranous siphon through the air-chambers, in relation to the maintenance of vital harmony 

 between the soft and testaceous parts, such likewise must have been enjoyed by the numerous extinct 

 species of the Tetrabranchiate Ccphalopods, which, like the Nautilus, were lodged in chambered and 

 siphonifcrous shells."— Zec/wre* vpon the Invertebratu, by Professor Owen, p. 331, 1843. 



