592 TRANS. ST. LOUIS ACAD. SCIENCE. 



Genus CYCLOGRAPTUS, nov. gen. 



Gr. kutlos, a disc; grapho, I write. 



In this genus, the frond consists of a circular disc which was 

 probably cup-shaped in its growing form, though flattened in a 

 concave manner in the rock. From the radicle many stipes radi- 

 ate through the non-celluliferous disc to its margin, and thence in 

 a free manner to some distance beyond. The whole frond resem- 

 bles a solid wheel, where the radiating spokes extend from the 

 centre regularly to beyond the circumference. The branches be- 

 yond the disc are celluliferous. The stipes have a central solid 

 axis. The substance is highly corneous, though in some places 

 replaced by pyrites. 



This genus somewhat resembles the discoid species of the 

 Graptolite Family belonging to the Qiiebec group. Yet all the 

 branches or stipes are short and relatively small compared with 

 the disc, which is circular (when flattened). The general ap- 

 pearance of this genus is another example of the similarity of 

 many of the more complex forms of graptolitic organisms which 

 existed in the Quebec and Niagara periods, though so widely 

 separated in point of time. 



I had often noticed the wheel-like stains in several rocks found 

 at Hamilton, but generally referred them to concretionary stains 

 in the rocks. It was only in December, :S79, that I obtained 

 two specimens and two casts whose characters could be deter- 

 mined. All of these specimens belong to one species. 



Cyclcgraptus rotadentatus, nov. sp. 



Plate 6. Figs. 6 & 6a. 



Frond circular, with numerous stipes radiating from a common 

 centre and projecting like a toothed wheel beyond the margin of 

 a non-celluliferous disc. The frond was probably cup-shaped 

 when growing, with the stipes projecting upwards like a row of 

 spines or of tentacles, but in the rock the fossil is flattened and 

 slightly convex. The stipes originate in the centre, and are con- 

 nected about half their length by their continuous non-cellulifer- 

 ous membrane. Each stipes after passing beyond their solid disc 

 divide into two branches about halfway between their extremi- 

 ties and the margin of the disc. The branches or stipes are tra- 



