Mahylaxd Geological Survey 145 



These specimens are mainly small and the hcst ones were obtained in the 

 arg-illaceous shales on tlie Williams Eoad about one-fourth mile east of tlie 

 Queen City Hotel, while othei's came from a ealcareous stratum at the iron 

 bridge over Town Creek about 31^ miles northeast of Okltown. 



Part of the specimens of this species considerably resemble Scliucher- 

 telUi cheiniingensis (Conrad) var. perversa Hall, to which they were at 

 first doubtfully referred. Further study led to greater uncertainty, and 

 finally the specimens were sent to Dr. J. M. Clarke for his opinion re- 

 garding their specific relationship. After an examination Dr. Clarke 

 wrote as follows : " I have studied the specimens of Orthothetes you 

 have sent and compared them with the types of 0. perversus. With re- 

 gard to these fossils, so far as they occur in the Devonic, it is easy to see 

 that the}' are in a certain sense ontogenetic exj^ressions of a broad specific 

 type, and it is often very difficult to draw lines among the specimens as 

 they have been drawn by their describers. These specimens show both 

 an extremely simple form of plication and a more complicated expression, 

 such as would naturally result from later growth. 0. perversus is such 

 a species in external character as this larger specimen witli intercalated 

 plications, and yet the other specimens with simple plications seem only 

 to express the more infantile condition longer continued. I hardly know 

 what we shall do with facts of this kind. Doubtless the specimens are 

 all of the same species and I should be disposed, personally, to cut the 

 Gordian knot by describing it as a distinct species, and if you call it 0. 

 variabilis you would doubtless tell the truth in its name. My species 0. 

 bellulus from the Marcellus shales is very close to the larger of these 

 forms and occasionally shows a simple equal plication of the smaller 

 shells, i. e., the shells pass through the same variations as do the Mary- 

 land, and yet I should hesitate to include them under that term, as the 

 Marcellus species is much more sparsely plicate." 



Occurrence. — Romney Formation, Onoxdaga Member. W. Ya. 



Central E. R. cut at 21st Bridge. Williams Road, 3^2 miles southeast of 



Cumberland. Hamilton Member. Williams Road, 14 mile east of 



Queen City Hotel, Cumberland ; Town Creek, 3^ miles northeast of 



10 



