son, this generic appellation ; * * I am glad that a modification 

 in the meaning of the word enables me to retain a name which 

 will always bring to the inquirer's recollection the long and suc- 

 cessful labours of Dr. Mantell." The candid reader may judge 

 from these and other passages whether I have wished to de- 

 preciate the labours of Dr. Mantell or his reputation. 



Second, as to the matter of fact. The question simply is, what 

 is knowledge of a class of animals. I apprehend that " know- 

 ledge " of any creature is not merely the sight, or bare handling, 

 or even giving an arbitrary name to a specimen ; it must imply 

 some knowledge of structure and functions, in the same way as 

 Professor Owen justly tells us that " the knowledge of the or- 

 ganized beings now called Polypi, as members of the animal king- 

 dom, is of comparatively recent introduction " (Comp. Anat. i. 

 p. 81), though these had been seen and handled on the sea-shore 

 for ages. I certainly must repeat the assertion that, previously 

 to the publication of my papers, papers as to which Dr. Mantell 

 himself has been pleased to say that " the subject has recently 

 been investigated by a gentleman of distinguished ability" 

 (Wonders of Geology, 6th ed. p. 638), the nature of these 

 beautiful fossils was " totally unknown" Neither Dr. Mantell 

 nor any previous writer had ever even suspected the existence of 

 any membrane whatever in the Ventriculidse. On the other 

 hand, < I have demonstrated that the basis of the Ventriculidse 

 is a simple unperforated membrane; that, therefore, the descrip- 

 tions so long before the world, and so often repeated, are funda- 

 mentally erroneous, the conclusions as to the oeconomy of the 

 animal being necessarily, therefore, as fundamentally erroneous " 

 (p. 48 note). In addition to this, and other points to which I 

 cannot now allude, I have discovered and described and figured, as 

 existing in this membrane, an entirely new form of animal struc- 

 ture; of which Dr. Mantell himself has said (somewhat in incon- 

 sistency with what he now considers as due to his courteous read- 

 ers) : " Of the accuracy of Mr. Toulmin Smith's beautiful mi- 

 croscopic examination of the intimate tissue of these zoophytes I 

 have, no doubt', and will only remark that the octahedral form, 

 represented as that assumed by the inosculating fibres of the 

 membrane of the Ventriculida3, is a very extraordinary anomaly in 

 animal structures" (Wonders of Geology, 6th ed. p. 638 note.) I 

 think Dr. MantelPs own words, addressed to the very readers 

 whom he now twice assures of his own accuracy, and whom he is 

 so anxious to treat with all due courtesy, are the best testimony 

 that he is doing me injustice. 



I am surprised that Dr. Mantell should speak of an " incon- 

 gruous assemblage " of forms. I might take almost any family 

 of either animal or vegetable kingdom to show the futility of 



