310 ANNALS NEW YORK ACADEMY OF SCIENCES 



general character or characters by which the Carboniferous species as a 

 whole differ from the Devonian species. In some instances, however,, 

 certain general types within a genus appear to be restricted to one sys- 

 tem of rocks or the other. Thus, the punctotus group of Producti is a. 

 distinctly Carboniferous development of the genus so far as known- 

 Now, the great bulk of the Bedford fauna, as will be seen from an ex- 

 amination of the table given on another page, belongs to types not char- 

 acteristic of either system. Most of them would not appear out of place 

 in either a distinctly Devonian or a distinctly Carboniferous fauna. In 

 such an association, one might say "This is a new species in this fauna"" 

 but not "This is a Devonian species" or "a Carboniferous species," as the 

 case might be. Thus most of the Bedford species, considered in their 

 broader relations, are ambiguous in deciding the Devonian or Carbon- 

 iferous affinities of an intermediate fauna. One might indeed take up 

 the Bedford fauna species by species and draw an inference from the 

 number of Devonian, of Carboniferous and of new species as to whether 

 the fauna should be grouped with the Devonian below or with the Car- 

 boniferous above. Such a careful canvass of the relationship of the dif- 

 ferent Bedford species would require more time than it has been possible 

 for me to give and would almost need be accompanied by a discussion of 

 each species, such as would be out of place in a paper of the present 

 scope. Besides this, as between closely related species in the Devonian 

 and the Carboniferous the conclusion reached in the identification would 

 many times be a matter of personal opinion. Comparisons sufficiently- 

 ample have been made, however, to show that many of the Bedford spe- 

 cies are new and that the Carboniferous alliances are at least not more 

 numerous than the Devonian. I propose, on the other hand, to point 

 out a few instances of larger groups than species, about the identifica- 

 tion of which there can be less room for personal differences of opinion 

 and which, because they do represent larger groups, carry more weight 

 than species themselves, for I take it that the horizon which marked the 

 extinction of the genus Spirifer would be more noteworthy than that 

 which marked the extinction of some one species of Spirifer, such as 

 8. Tceokuk. Of such peculiarly pre-Carboniferous types, the first in my 

 list is the genus Pholidops, which has never the world over I believe been 

 found at horizons recognized as Carboniferous. The next on the list is 

 Delthyris, which has usually been identified in the Bedford fauna as 

 Spiriferina and which I have already discussed at some length. This is 

 a distinctly Devonian type of Spirifer and with one or two exceptions, to 

 which reference will be made later, has never been cited from Carbon- 

 iferous rocks. Next come the types which I have called Nucleospira ? 

 sp. and Camarospira ? sp. 



