308 ANNALS NEW YORK ACADEMY OF SCIENCES 



farther reduced by the fact that Schuchertella (Ortlwthetes) crenistria 

 is a strictly European species, though the name has been applied to sev- 

 eral forms in the Waverly which might be regarded as a single species or 

 split up on rather small differences into several, according to the dispo- 

 sition of the investigator, and of which some are doubtfully distinct even 

 on trivial characters from the common Chemung form Schuchertella che- 

 mungensis. 



From my own experience if any brachiopods are less satisfactory for 

 identification and therefore for correlation than the Schuchertellas, they 

 are the Discinoids, to which Oehlertella pleurites belongs. On the whole, 

 however, this species, which is a rather common "Bradfordian" type, 

 must be regarded as Carboniferous rather than Devonian in its bearing. 



The Pectinoids are greatly diversified in shape and especially in exter- 

 nal ornament, and a number of fairly distinct groups can be made on 

 superficial characters, some groups small and peculiar, others more corn- 

 man and generalized. To the commonest and most general of these, 

 Crenipecten winchelli belongs. Now species superficially very similar to 

 this are found in other genera, such as Pecten, Aviculipecten, Deltopec- 

 ten, so that, as the hinge characters are very seldom to be observed, it is 

 usually impossible to determine with certainty the generic group to which 

 these commonplace Pectens belong, and this fact naturally brings into 

 doubt the specific identification even when the superficial resemblance is 

 close. The identification in this case is made without a query, however, 

 and Crenipecten winchelli must be regarded as a distinctly Carboniferous 

 type. 



Glossites amygdalinus and Sphenotus ceolus are also distinctly Carbon- 

 iferous species, but in their case the identification is admittedly doubtful. 



I have not consciously made little of the evidence presented by Mr. 

 Butts, yet two of the species in his list are obviously identified with doubt 

 and it seems to me that of the remaining five the three invertebrates and 

 possibly also the two fishes belong to types in which the discrimination 

 of species is difficult and unsatisfactory even with very good material. 

 Furthermore, in interpreting the evidence I would think it wiser to ex- 

 tend the range downward of seven species rather than extend the range 

 upward of 52. 



In seeking to determine whether the Bedford shale should be classed as 

 Devonian or Carboniferous, the problem is not perhaps whether it carries 

 a Chemung or a Kinderhook fauna; it is not a mere matter of correla- 

 tion, though correlation is involved. The fact seems to be that the Bed- 

 ford shale represents part of an interval between the base of the Missis- 

 sippian and the top of the Devonian as those systems have usually been 



