184 Mr. Toulmin Smith on the Ventriculidse 



" resisting suppuration, maceration, and other modes of destruc- 

 tion, for a great length of time*." 



I have already stated that I had previously satisfied myself of 

 the existence of a distinct polyp-skin or epidermis. A peculiar 

 appearance of corrugation, very difficult to describe but always 

 present in good casts, and with a vacant space between it and the 

 actual fossil, left this beyond a doubt, though at that time no spe- 

 cimen had been found showing the remains of the epidermis 

 itself preserved on the actual fossil. In specimens since found 

 with remains of epidermis preserved, there is, of course, no such 

 vacant space. Attached to this epidermis and of a similar nature, 

 and at least as durable f as itself, there evidently existed during 

 the life of the animal hair-like processes scattered over a large 

 part of its surface. 



Plate VIII. figs. 4 and 5 show examples of the appearances of 

 casts of two very different species of Ventriculidse, in each of which 

 these perforations are present. It will be seen that a different 

 arrangement of them exists in the two cases. 



It would be only tedious to the reader to carry him through 

 the whole process of induction, by which, not through any hasty 

 conclusion, but as the result of careful and very cautious inves- 

 tigation, the reality seemed to force itself upon me that the 

 sources of these perforations corresponded to those curious move- 

 able processes which exist on the surface of some few of the 

 higher zoophytes, and which have been well described by Prof. 

 Reid %. The determination may seem obvious enough on its an- 

 nouncement thus in a few words, but it was not so easy to be 

 made. 



After I had satisfied myself as far as I was thus able upon this 

 point, I determined, if possible, to test the correctness of the 

 conclusion. Taking, therefore, a very fine specimen of Membra- 

 nipora pilosa§, in which the processes, exhibiting every character 



* Elliotson's * Physiology,' 5th ed. p. 270 ; and see Todd and Bowman's 

 1 Anatomy and Physiology/ vol. i. p. 414. The appearance of the polyp- 

 skin, as preserved by the deposit in it of sulphuret of iron, and examined 

 under the microscope, has been recognized by some of my friends wholly 

 unfamiliar with these or other fossils as bearing a striking resemblance to 

 the human epidermis examined in the same way. 



f I have found by actual experiment that, at least in some species, the 

 hair-like processes of recent polypifers are, though hollow, less easily de- 

 structible by maceration in liq. potasses than are the other parts of the epi- 

 dermis. And I cannot avoid noticing here, that on such maceration a gra- 

 nular appearance was assumed very similar to that of the Ventriculidse. It 

 is unnecessary to dwell on this effect of the potash contained in the same 

 felspar rocks to whose disintegration the siliceous fluid has been ascribed. 



J Ann. and Mag. Nat. Hist. vol. xvi. p. 385, &c. 



§ In this specimen there are all the parts described by Prof. Reid as ap- 



