214 ROYAL SOCIETY OF CANADA 



Certain other associated 'species signify affinity with tlie lower Hel- 

 derbergian fauna: such are 



Cheetetes sphaericus, 



Orthis (Ehipidomella), cf. oblata, 



Orthis (Dalmanella) subcarinata. 



Orthis, cf. quadrans, 



Orthothetes, cf. Woolworthana, 



Uncinulus, cf. mutabili's, and 



Rhynchonella eminens. 



'These are forms represented in the Middle Devonian by closely re- 

 lated species, except the latter two which are of distinctly Lower De- 

 ronian type. This second set of species therefore may be considered as 

 expressive of environmental conditions rather than age alon^, since the 

 conditions expressed by the limestone are dissimilar from those of the 

 Oriskany sandstone, and more like either the Lower or Upper Helder- 

 berg formation occurring below and above the Oriskany sandstone of the 

 JNew York section. These two parts of the fauna taken together there- 

 fore signify that we are dealing with a fauna nearly related to the Oris- 

 kany, but differing from it by species which are more closely related to 

 tjpecies of the limestones which lie either below or above the) Oriskany of 

 the typical section. Adding to this evidence the other species wliich 

 show a distinct affinity with Middle Devonian forms: viz- 



Chonetes hudsonicus metatype gaspensis, Clarke. 



Spirifer montrealensis sp. nov., H. S. W. cf. S. granulosus. 



Spirifer pennatus var. Helense, v. nov., H. S. W. 



Modiomorpha helena sp. nov. H. S. W. (cf. M. concentrica). 



Palaeoneilo helena sp. nov., H. S. W. ("cf. P. Maxima, Clarke,") 

 and the conclusion drawn is that the St. Helen's fauna (No. 1) followed 

 the typical Oriskany rather than preceded it. In age it is probably 

 nearly equivalent to the Schoharie grit of the New York series, but the 

 horizon represented is not later than the early stage of the Onondaga 

 limestone. Certainly not as recent as Hamilton, tho^ showijng traces of 

 ancestral lines of species which are conspicuous in the Hamilton fauna 

 of New York. 



Critical Study of the Species. 



Since the naming of fossils is subject to error on account of imper- 

 fection both of the specimens and the definitions, and as fossil organisms 

 are 'subject not only to variation but to evolutional modification, the 

 value of conclusions drawn from a list of specific names greatly depends 

 upon the care used in applying the names and perhaps still more upon 

 the point of view of the author selecting them. As therefore the age of 



