220 PALEONTOLOGY OF OHIO. 



Paleophyllum divaricans, Mcholson. 



Plate 22, figs. 10, 106. 



Corallum usually free, sometimes apparently attached, compound, 

 formed of conical, turbinate corallites, which are produced by lateral 

 gemmation, or rarely by fission, and which are directed outwards from 

 the parent, usually at a more or less open angle, and are never in actual 

 contact with one another. The number of corallites in the corallum, so 

 far as observed, varies from two to six. Septa from fifty-eight to sixty- 

 two, alternately large and small, the large ones becoming twisted as they 

 approach the center of the visceral chamber, where they unite with one 

 another laterally, and form a more or less developed central mass of 

 vesicular tissue. No dissepiments nor columella. Tabulae unknown. 

 Wall with a well developed epitheca, with longitudinal ridges corre- 

 sponding with the septa Avithin, and also with faint encircling strife and 

 a few shallow annulations of growth. Calice deep, with a flattened space 

 at the bottom. Free edges of the septa not furnished with spines or 

 denticulations. Apparently no fossette. 



The best preserved specimen which has come under my notice consists 

 of two corallites, one budded from the side of the other nearly at right 

 angles. The largest corallite has a length of nearly ten lines, a diameter 

 of calice of seven lines, and a depth of calice of four lines. Another 

 specimen consists' of six nearly equally sized corallites, apparently pro- 

 duced by parietal gemmation, and having a length of five or six lines, 

 and a diameter at the calice of about five lines. Another specimen con- 

 sists of two large corallites which appear to have been produced by 

 fission, being attached only by their pointed bases, and being nearly in 

 contact with one another. The length of the largest of these corallites 

 is more than an inch and a half, and its diameter at the calice is ten 

 lines. Another specimen, precisely similar in its mode of growth, is at- 

 tached to the dorsal valve of Rhynchonella dentata, Hall, the length of the 

 largest corallite being only three lines, and the diameter of the calice 

 the same. 



The specimens from which the above description was taken in most 

 respects closely resemble Streptelasma corniculum, Hall, especially as con- 

 cerns their twisted septa ; but they possess a much smaller number of 

 septa (if specimens of the same size be compared), and they are always 

 rendered composite by the production of lateral buds or by cleavage. 



With Palxophyllum rugosum, Billings, the present species can not be 



