Niagara group. 1 15 
Fig. 4 m . A small specimen, showing a section through the centre, with deep transverse cup- 
form septa. 
Fig. 4 n. This individual shows apparently lateral budding, but the appearance is probably due 
to the cessation of growth at the point o, where the animal had contracted the cup; 
and from this cell originated three young polyps, the stronger growing more up¬ 
rightly and pushing out the others to one side. 
Position and locality. In the lower part of the Niagara limestone, associated with the pre¬ 
ceding and following species. {State Collection. Collection of Col. Jewett, &c.) 
Genus DIPLOPHYLLUM {nov. gen.). 
[Gr. <WX oog, duplex, and ipuXXov, folium; in allusion to the duplex character of the cell.] 
Simple, ramose or aggregate cylindrical stems; corallum composed of two distinct portions, 
the inner transversely septate, thd outer with fine transverse dissepiments uniting the lamellae 
which are continuous to the centre ; cell deeply concave in the centre, and separated from the 
outer portion by a distinct rim ; both the inner and outer portions stellate with the same num¬ 
ber of rays. 
The distinguishing features of the genus are the difference in the characters of the central 
and marginal areas of the cell, which are distinctly separated from each other, as shown in 
longitudinal sections. 
This genus is apparently related very nearly to the Diphyphylltjm of Lonsdale (Geology 
of Russia and the Ural Mountains, Appendix), preserving also more intimate relations to 
Cyathophyllum, Columnaria and allied genera, but requiring separations upon sufficient 
grounds, if we are to give to the numerous forms of this family names of any definite signi¬ 
fication. The generic names proposed for the species here described sufficiently indicate their 
difference from the Cyathophyllae ; and instead of applying that generic term to all the 
Silurian corals having any general resemblance to the genus, we have the means of giving 
geological value to the type. 
I may remark in this place, that thus far we have not found a single species of the Genus 
Cyathophyllum, as limited by recent authors, in any rock below the Onondaga limestone. It 
seems, therefore, that notwithstanding the representatives of this type came into existence at 
very early geological periods, still no species having the structure of Cyathophyllum ceratites 
of Goldfuss is known throughout the Silurian rocks of America, if we limit the application of 
that term to those rocks below the Oriskany sandstone. 
The rocks of the Niagara period, from which these fossils are described, is regarded as 
equivalent to the Dudley or Wenlock formation of England ; and although we have the family 
Cyathophyllidea represented by Streptelasma, Caninia, and the three new genera here intro¬ 
duced, we have no true Cyathophyllum ; nor have we Cystiphyllum, or Heliophyllum at 
the same period. These are all typical of certain geological periods ; and by attending more 
minutely to their structure, they become valuable evidences of the age of the rock in which 
they occur. 
jCxXC. 71 i 
Ilf 
IP 
