Descriptions of Neiv Genera and Species of Fossils. Tl 



lines. Cell mouths not clearly determined, but appear to be situated 

 near the middle of the cell. 



This form lias only beeu observed, incrusting Streptelasnia coraicu- 

 lum. On account of the great delicacy of the fossil, the fronds them- 

 selvps are rarel}' found, but instead we find a series of impressions on 

 the exterior coat of the Streptekisma, which very well represent the 

 fronds and cells of the same. 



Formation and iocalit}': the type specimens were found in the upper 

 part of the Hudson River Group, at Clarksville, Ohio. 



Collectors: H. E. Dickhaut, E, O. Ulrich. 



CuiETETES coMi'UESSus, u. sp. (Plate VII., figs. 25, 25«, 256). 



l^iy .—Compressus , compressed.] 



Polyzoary composed of small, very thin fronds, carrying the cell- 

 mouths on both sides; thickness of fronds varying from one half a 

 line to one line. 



Surface smooth. Tubes slightly oblique to the surface, opening by 

 somewhat elongated apertures. Cell orifices nearly of equal size, cir- 

 cular to oval, and arranged in diagonal rows, eight to ten occupying 

 the space of one line; occasionally a small septal tooth is developed in 

 some of the tubes, projecting from the wall into the aperture. Inter- 

 cellular space of variable thickness, apparently occupied by but few 

 minute cells. 



In longitudinal sections the tubes are short and approach the sur- 

 face in a regular curve, a line drawn from the commencement of a tube 

 to the aperture, forming an angle of about forty-five degrees with the 

 surface; in the center of the frond the tubes are crossed by remote 

 tabulae, but as they near the surface the diaphragms become much 

 more numerous, and here th&y are placed one third tube diameter 

 apart. A few of the tubes are divided into halves by a delicate, wav^-, 

 vertical septum ; in one half of the tube the tabuljB are always more 

 or less curved, while in the other half the3' are straight. 



The general aspect of this species is somewhat like that of small 

 specimens of C pavonia and C. decipiens, but those species grow in 

 double leaves, with a divisional lamina between them. In the shape 

 and arrangement of the tubes they are also diff'ereut. It is so easily 

 distinguished from the other frondescent species of the genus, that 

 no comparison vvith any of them is necessary. 



Formation and locality : the specimen figured is from the cabinet 

 of the author, and was found by Mr. J. Nicklas, at Cincinnati, Ohio. 



