REPORT OP THE STATE PALEONTOLOGIST 1901 



527 



striking number of new forms altogether foreign to deposits 

 of earlier age. They are thus in this sense and for the section 

 we have under consideration, superstitial species, that is, purely 

 survivors which have held their ground in the face of organic 

 modifications and change of physical conditions going on about 

 them. 



3 The Wolf creek conglomerate marks the dawn of a number 

 of species. Thus a species of the brachiopods, Oehlertella, not 

 to be distinguished from O. pleurites which abounds in the 

 Bedford shales of Ohio, appears here and also in the overlying 

 stratum no. 7. Of the Leptodesmas, L. or odes here appears; 

 also Modiola praecedens and a considerable number of 

 the Ptychopterias; some are identifiable with previously known 

 species and others appear to be of variant form. With a single 

 doubtful exception all these Ptychopterias appear at this hori- 

 zon or above it. Palaeanatina typa also makes its ap- 

 pearance here. The effect however of this conglomerate in the 

 strata is less marked in this respect as the point of departure of 

 novel forms of the series than as a dividing line in the succes- 

 sion of faunas. We may indicate the contrast in the aspect of 

 the faunas above and below this line by the following columns: 



Above base of Wolf creek conglomerate 



Agelacrinus buttsi 



A., polita 

 Camarotoechia allegania 



Oehlertella pleurites 



Below base of Wolf creek conglomerate s 



Athyris angelica 

 A. cora 



Chonetes scitula 



Schizophoria 2 sp. 

 Productella 5 sp. 

 Edmondia 3 sp. 

 Leptodesma potens 



" var. juvenis 



mortoni 



sociale 



matheri 



longispinum 



protextum 



spinigerum 



