EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 



115 



d'Orbigny, the type of Bayle's genus Trigeria, was probably present in the 

 Oriskany fauna of Maryland. This is a strongly plicated rensselaeroid, 

 throughout of similar aspect to these under consideration save in minor 

 details. To the same group R. portlandica belongs and in the work 

 cited was referred to the genus Trigeria. 



The genus Trigeria means a strongly plicated rensselaeroid with the 

 hinge plate in an elemental condition, i. e. perforated, but with cardinal 

 process slightly developed if present at all, and a cardinal area more or less 

 distinctly retained on both valves. The genus stands to Rensselaeria 

 (R. ovoides) in the relation of a neanic to an ephebic condition. R. 

 a 1 1 a n t i c a, in its progressed expres- 

 sion even though retaining the primi- 

 tive structure of the cardinal areas, can 

 not be brought within that group, and 

 Trigeria can not be construed as a valid 

 generic term in the face of the facts 

 here adduced. 



In the closest alliance with the 

 Edmunds Hill and Dalhousie shells are 

 specimens which I have received from 

 Prof. E. Kayser labeled R. strigi- 

 c e p s Roem. from the Siegen grey- 

 wacke, at Siegen (Coblentzian). Though 

 the shell is persistently smaller than those referred to, it is of the same 

 contour, degree of plication and interior structure, emphasizing again the 

 " Trigeria" characters. Precisely what is the relation of this small form 

 from Siegen to the large, elongate, more characteristic examples of 

 R. strigiceps from the Taunus quartzite at various localities which bears 

 so strong a resemblance to R. atlantica, the writer is not in position 

 to say, but it may prove to be the same as that we have here indicated. 



Rensselaeria 

 and cardinal 

 Herzdorf 



strigiceps Roemer. Dorsal 

 views. Siegen greywacke, near 



Rensselaeria nov. 



Plate 29, figure 19 



A large convex subcircular ventral valve presents a distinct departure 

 from the other forms of the fauna in its shape and very finely lineate 

 surface. 



Locality. Edmunds Hill. 



SPIRIFER 



The recent labors of Kayser, Drevermann and Scupin have done much 

 to clear up the difficulties of identification among the many species of Ger- 

 man Lower Devonic Spirifers. Too often among the earlier writers on 



