WHAT ARE THE YEIfTKICULITES ? 



165 



Then, and not till then, shall we have the proper data for replying 

 to our question, What are the Yentrtctjlites ? 



We would say a few words on the rigidity of the ventriculites. We 

 know there is a tendency amongst geologists to consider the ventricu- 

 lites as of flexible structure when living. This notion, originating with 

 the late Dr. Mantell, has been perpetuated by their occurrence as 

 fossils in every variety of shape, apparently of dilation or contraction. 

 On the other hand, it has been urged that the attachment of oyster 

 and dianchora shells and serpulse prove that they must have been 

 rigid, because otherwise such parasites could not have lived and 

 grown on them, as the growth-lines of such shells prove them to 

 have done. 



For our own part we do not see the force of either argument, for 

 the apparent expansions and contractions may be, as we believe 

 them, a mere accidental kind of growth of the ventriculite, which had a 

 general tendency to flatten or become disk-like with age. We are 

 not aware that any closer approximations of the constituent fibres 

 in the so-regarded contracted specimens, or of their dilations in the 

 equally hypothetical expanded ones, has ever been observed; and, 

 moreover, such a complicated and &r«cec? structure, which is pointed 

 to as a wonderful example of the Creator's engineering skill to pro- 

 duce a comparatively strong framework out of the slenderest ma- 

 terials, would lose its apparent object, and certainly must have been 

 one of the most awkward and intractable of any which could have 

 been conceived for such a purpose as elasticity or flexibility. 



As to the growth of shells upon ventriculites, of all the examples 

 we have seen, and they are many, most were decidedly attached to 

 dead skeletons. Some few we have seen pitted by the marks of 

 the corrugations and pores of the skin, and such evidently shows 

 that the oyster or dianchora grew on the living ventriculite, the fry 

 fixing themselves most probably, in the first instance, in the inter- 

 spaces between the pores, if the ventriculite was a sponge, or between 

 the tentaculated heads, if the ventriculite was a polypiferous organism. 

 In some instances, and we figure an example (see fig. 1, p. 161), the 

 oyster or dianchora growing for some time on the living skin, grew on 

 after the death of the ventriculite ; for, if Dr. Bowerbank's theory of 

 the sponge-origin of flint be true, and it certainly is the best hypothe- 

 sis yet propounded, the amorphous sponge growth enveloping the 

 ventriculite, and since converted into flint, was prevented growing 

 over those shell-fish by the currents produced by their gills, and the 

 motive action of their unattached valves in opening and closing ; conse- 



