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PALAEONTOLOGY OF NEW YORK. 
The erroneous reference of this species has but recently been corrected, in part, by Mr. 
A. F. Foerste, f who has pointed out some of the differences already mentioned, and has 
proposed to retain the species (as it stands in the list) associated with 0 . calligramma, var. 
flabelliles. While indisposed to continue a resupinate shell in this association, the necessity 
of another name for the American species is evident. 
The following arrangement will indicate the relations of Orthis fldbellites to the group of 
Orthis callactis, Dalman, and that of Orthis pectinella , Emmons : 
ORTHIS, Dalman (as restricted). 
I. Group of Orthis callactis, Dalman. 
* 0. costalis, Hall . Chazy. 
* 0. orthambonites, Billings . Quebec. 
* 0. Euryone, Billings . Quebec. 
* 0. Hippolyte, Billings . Quebec. 
* 0. disparilis, Conrad . Trenton. 
* 0. tricenaria, Conrad . Trenton and 
Hudson River. 
* 0. Davidsoni, de Verneuil . Niagara. 
0. flabellites, Hall. 
Niagara. 
DINORTHIS. 
IV. Group of Orthis pectinella, Emmons. 
* 0. pectinella, Emmons . Trenton. 
* 0. pectinella, ^ m 
var. semiovalis, HALL. irenton. 
* 0. Sweeneyi, N. H. Winchell, Trenton. 
f Proceedings Boston Society Natural History, vol. xxiv, pp. 308-312. 1890. 
The following tabular arrangement of the generic subdivisions of the 
Ortsidje will show the geological range of each one of the subdivisions, and 
of the entire family: 
