OKISKANY FAUNA OF BECRAFT MOUNTAIN 91 



A similar outburst of species is afforded by the genus Tremato- 

 s p i r a (T. multistriata, T. costata, T. perforata, T. sim- 

 plex). The genus is here culminant, the small T. c a m u r a of the 

 Niagara being the only preexisting species. 



Parazyga is known only here and in the Mesodevonic. 



Nucleospira is here near its culmination with a considerable 

 subsequent development into the Mesodevonic. 



Stenoschisma is not elsewhere known. ' 



Uncinulus attains its culmination here (U. rautabilis, U. 

 abrupta, U. vellicata, U. nucleolata). 



Eatonia is known only in the Helderbergian and Oriskany 

 faunas. 



Sieberella (S. galeatus and S. pseudogaleatus) occurs 

 widespread in the upper Siluric, and a common middle and upper 

 Devonic shell is referred by European paleontologists to S. galeatus. 



Rensselaeria (R. mutabilis, R, aequiradiata, R. ellip- 

 tica, etc.) makes its first appearance here and disappears with the close 

 of the Oriskany. 



Trigeria is known in America only in the Helderbergian (T. 

 portlandica Square lake Me.) and Oriskany (T. gaudrp Oehlert, 

 Cumberland Md.) faunas. 



Cryptonella begins its existence in the Helderbergian (C. e x • 

 i m i a ) and is continued into the lower Carbonic. 



Bryozoans. The sum of the characters of this element points 

 strongly toward the Devonic. Rhombipora, Diamesopora, 

 Coelocaulis, Callotrypa, Fistulipora, Lichenalia, have 

 a few representatives in the Siluric, but are here much progressed 

 toward or to their culmination. Paleschara, Stictopora, Cra- 

 nio p o r a , abound in later faunas. The feuestelloids ( F e n e s - 

 tella, Unitrypa, Hemitrypa, Polypora) are relatively few 

 in the Siluric, greatly abound in the Helderbergian, but attain their 

 culmination in the Mesodevonic. The genus Thamniscus makes its 

 first appearance here. 



Crinoids. Edriocrinus occurs only here and in the Oriskany. 



