308 
PALAEONTOLOGY OF NEW-YORK. 
Capulus, Pileopsis, AcRoctiii, and Platyceras. 
In the work entitled “ Figures and Descriptions of the Palaeozoic Fossils 
of Cornwal, Devon and West-Somerset,” by Professor Phillips, published 
in 1841, he has proposed the Genus Acroculia to include certain fossils 
which had been referred to the Genus Pileopsis, and to which, he re¬ 
marks, they “ offer but slight analogy.” Plis description is as follows : 
“ Provisional character. Obliquely spiral; the apex free, the aperture 
“ ample, without columella : a sinus in the right lip.” 
This generic distinction has been acknowledged by some palaeontolo¬ 
gists ; but, more recently, both Continental and English naturalists have 
referred all these forms to Capulus or Pileopsis, which are regarded as 
synonymous. 
Previous to the publication of the work of Professor Phillips cited 
above, Mr. Conrad, in his Report on the Palaeontology of New-York for 
1840 ( p. 205), proposed the generic name Platyceras, with the following 
remarks : 
“ I propose to group in this genus the Pileopsis tubifer ( Sowerby ), P. vetusta 
a ( Sowerby), the JVerita haleotis ( Sowerby), and perhaps Bellerophon cornuarietes. 
<■< The shells are suboval or subglobose, with a small spire, the whorls of which are 
« sometimes free and sometimes contiguous : the mouth is generally campanulate 
« or expanded. I have not seen a species above the Silurian rocks, though they 
c probably occur above them in Europe*, and they are never found in the Lower 
« Silurian strata : they characterize the middle portion of the system.” 
The generic description of Mr. Conrad is more comprehensive than 
that of Professor Phillips, as it includes shells with the volutions free or 
contiguous. Both authors, however, have designated among the typical 
* At the time this was written, the Hamilton and Chemung groups were regarded as a part of the 
Silurian system by theNew-York geologists, the Hamilton group being recognized as the equivalent of the 
Ludlow rocks of England; and we have yet seen no sufficient reasons to regard it otherwise. Mr. Conkad, 
in including the Bellerophon cornuarietes in the Genus Platyceras, must have regarded it as an un- 
symmetrical shell. 
