90 
PALEONTOLOGY OF NEW YORK. 
group; A. Cora, Hall, of the Hamilton group; A. vi'tata,* Hall, of the Cornifer- 
ous limestone and Hamilton group; A. Angelica, Hall, of the Chemung group; 
A. lamellosa, LtWeille, of the Waverly and Keokuk groups; A. incrassata, Hall, 
of the Burlington limestone, and A. Hannibalensis, Swallow, of the Choteau 
limestone. 
Subgenus CLIOTHYRIS, King. 1850. 
This name was introduced by Professor Philllps, in 1841,f as a substitute for 
Dalman’s term Atrypa, which this author did not regard as appropriate. The 
term was not subsequently used by him, nor was any typical species mentioned, 
so that in its original application the term has no meaning. Subsequently, and 
perhaps unfortunately, Professor William King revived the name,:|: giving a 
careful diagnosis and specifying as his type of the genus, Atrypa pectinifera, J. 
de C. Sowerby. 
His description was : “ Generally lenticular in form ; minutely punctured ; 
with variously characterised projecting laminge of growth ; Spirals pectinated ; 
Dental plates large and separated ; Crural base perforated; Foramen situated at 
the point of the umbone, and open inferiorly by the fissure.” 
At this date the genus Athyris was not closely restricted or well understood. 
King followed McCoy in regarding Terebratula concentrica, von Buch, as its type, 
and demonstrated, though imperfectly, the existence of a process connecting 
the spiral coils of the shell. 
Atrypa pectinifera is a Permian species which varies from the structure in the 
typical division of Athyris in the following respects; The surface ornamenta¬ 
tion consists of broad, thin, lamellar expansions which are divided almost, 
and sometimes quite to their bases, into long, flat spinules; hinge-plate nar¬ 
row and rather acutely triangular; the primary lamellm are attached to the 
* These three species are pretty constant in their differences, the first being transverse, squamous forms, 
the others more orbicular and retaining but traces of the laminae. The species present variations which 
are included by European palaeontologists within the limits of Athyris concentrica, von Buch. 
t Palaeozoic Fossils of Cornwall, Devon and West Somerset, p. 55. 
J The Permian Fossils of England, xr. 137. 
