95 



in its most aged form. A comparison of any of the forms we have re- 

 ferred to, may, by placing ahnost any two shells of different sizes in 

 juxtaposition, so that the curves of their beaks shall be as nearly as 

 possible parallel, will exhibit the same difference of degree between 

 them, in quite as satisfactory a manner. 



The names by which the numerous varieties have been hitherto 

 known, and under which they are figured, may of course always admit 

 of a certain use, as those of varieties only of 6. incurva, as which they 

 ought to be generally recognised. We have only further to remark, 

 that the repetition of the differences of character specified by various 

 writers in the forms which it has been our principal object to prove to 

 be varieties of one species only, would be, in connection with the 

 artistic illustrations so ably rendered by Mr. Bone, and the preceding 

 observations, superfluous. We simply invite attention to the fact, that 

 not only is there no clear distinction between them when studied in a 

 fairly selected series ; that no particular form is special to any portion 

 of the Lias of which we have yet treated stratigraphically ; but that 

 in our district, wherever Gryphites numerously occur, all the forms 

 most widely diverging from the ordinary type of G. incurva are found, 

 presenting differences from it, so infinitely modified as to make arbitrary 

 separation between them of specific value, quite as unintelligible as 

 absurd. These observations may be applied with equal propriety 

 to other species and genera of shells equally common in the Liassie 

 strata. 



The accident which prevented the ^vriter being present to read this 

 paper, has also prevented his perfecting his references to the next 

 species in stratigraphical order, which will be made the subject of a 

 further communication to the Club. 



