MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
93 
the structure of a Whitfieldella. Under the name Hindella um- 
honata Billings Hall and Clarke figure specimens from the same 
locality as Athyris umhonata Billings, but representing outlines 
closely similar to those of Athyris prinstana Billings, both of 
which had been described by Billings from the same locality 
and horizon on Anticosti island. Hall and Clarke made these 
supposed specimens of Athyris umhonata the type of their new 
genus Hindella, However, the Brassfield specimens appear 
to be distinct forms of Whitfieldella, so that, if Billing^ s species 
Athyris umhonata is identical with the form so recognized by 
Hall and Clarke, regarding which there is some possibility of 
doubt, then the term Hindella umhonata is not suitable for the 
Brassfield form, and the term Whitfieldella umhonata might 
prove misleading. Possibly the Brassfield species is closely 
related to Whitfieldella cataractensis Williams from the Mani- 
toulin dolomite and Cabot Head shale of the Cataract formation 
of Ontario. 
Parastrophia sparsiplicata (Poerste) 
Cyclospira ? sparsiplicata Sp. nov., Geol. Surv. Ohio, 7, 
1895, p. 593, pi. 37a, figs. 18 a, b. 
The chief feature of this shell is the presence of a median fold 
on the more strongly convex valve, the one whose beak overtops 
that of the other valve. This median fold bears two plications 
anteriorly, and an additional plication is faintly indicated on 
each side of the fold. No structure of this type exists in the 
genotype Cyclospira hisulcata (Emmons). However, in Para- 
strophia the brachial valve overtops the pedicel one. There is a 
tendency toward the development of a median fold with an 
even number of plications on this valve, and lateral plications 
occur. Therefore, it is regarded as much more likely that the 
Brassfield specimen in question belongs to the genus Parastrophia. 
