LOWER CARBONIFEROUS FOSSILS. 



495 



The fact that the entire Coal Measure series is lacking in this region, 

 or, if represented at all, finds expression in the unfossiliferous Quadrant 

 quartzite, makes it probable that the same forces which resulted in the non- 

 deposition or removal of the overlying formation affected the later portion 

 of the Lower Carboniferous time in the same way. 



Table .showing the representation of zoological groups in the Madison limestone fauna. 



Protozoa 



Sponges 



Ccelenterata 



Crinoidea 



Bryozoa ■... 



Brachiopoda 



Lamellibranchiata 



Gastropoda 



Trilobita 



Total 



Identified 



species. 



species. 



1 



1 



1 



1 



7 



6 



2 



1 



10 

 47 





43 



2 



1 



8 



1 



2 



2 



New 

 species. 



"Waverly 

 species'. 



1 





1 







5 



i 



i 







14 



29 

 1 









It will be seen from the foregoing table that an unusually large per- 

 centage of the fauna of the Madison limestone, not only in the number of 

 specific types, but in the abundance in which they are found, consists of 

 brachiopods. Most conspicuous for their rarity are the lamellibranchs, 

 of which only two specimens, representing two different species, 1 have 

 been collected. This is, perhaps, explained by the consideration that the 

 Madison limestone is usually rather pure in composition, no true shales 

 occurring interbedded with it. On the other hand, crinoids, which Ave 

 might expect to find abundantly in such extensive calcareous deposits, are 

 also comparatively rare. Other organic types appear, perhaps, in not far 

 from the average proportion. 



Two localities are interesting as presenting a local or perhaps more 

 than local development of the Madison limestone fauna. One, the cherty 

 limestone of Crowfoot Ridge, Gallatin Rang-e, forms the upper portion of 

 bed 24 of the section. The fauna consists of Productus semireticidatus, Meno- 

 jiJii/Uuiii (?) excavatum, Ncdicopsis (?) sp., Platyceras form a, Cliothyris roissyi, 

 C. crassicardmalis, Splrifer striatus var. madisonensis n. var., Spirifer centronatus, 



■One of these, very fragmentary (but perhaps referable to Cjipricardinia eonsimilis Hall or C. 

 unitula Herrick), is not mentioned in the report following. 



