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PALEONTOLOGY OF NEW YORK. 
Axis very prominent, semi-cylindrical. 
Pleura, flat for about one-half their width, thence sloping gently to the 
margins. 
Pygidium very elongate-triangular, the length being equal to the width. 
The axis tapers to an obtuse termination considerably within the scarcely 
thickened border; composed of twenty-two annulations, which are vertical 
on the sides, but have a gentle anterior curve toward their summit. 
Pleura flat near the axis, thence curving someAvhat abruptly outward and 
downward; bearing twelve annulations, which terminate in a broad, sloping 
border abruptly recurved at the edge. 
Surface finely granulose. 
Observations. There exists a great deal of doubt both as to the generic status 
and the geological age of this species. The original and type specimen was 
presented many years ago by the Rev. Mr. Nash, of Des Moines, Iowa, together 
with specimens of Phacops rana, and was said to have been found in association 
with the latter at some point to the north-east of that place. This was the 
only specimen of the species known until certain others were described by 
Mr. H. S. Williams {loc. cit.) from a blue limestone near Madison, Greenwood 
county, Kansas, and he has suggested that these may have been derived from 
rocks not older than the Carboniferous. Mr. Williams’ specimens were obtained 
from Mr. Edwin Walters, of Hickman, formerly of Madison, Kansas, who, in 
response to inquiries, writes that he has found this species in association with 
Phacops bufo {rana). Admitting its association with this well-known and 
characteristic fossil, its geological age would appear to be that of the Hamilton 
group. 
On the other hand the species, in many important structural features, is 
more closely related to the Carboniferous Phillipsia than to typical forms of 
Proetus. The possession of but nine thoracic segments, which appears to be a 
normal feature of the species at maturity, is known in but one other species of 
Proetus, viz., P. sculptus, Barrande, from the etage G. For the genus Phillipsia 
this is the normal number. Moreover, the oval, slightly constricted glabella, 
