PALAEONTOLOGY. IO9 



ton, Indiana ; the stems are of longer cylindrical growth, often 

 curved and geniculated ; their calyces rarely exhibit a naked dia- 

 phragm in the bottom, and the crenulated lamellae generally reach 

 to the centre. The surface of the stems is in both kinds longitu- 

 dinally ribbed by septal striae. 



CLISIOPHYLLUM, Dana. 



Simple conical polyp cells with the general structure of Cyatho- 

 phyllum, differing from it in the shape of the calycinal bottom. 

 Radial lamellae linear, with prominent free edges within the end 

 cells ; the interstices between the lamellae are traversed by trans- 

 verse, vesiculose plates, but these do not fill the interstices up to 

 the margins of the lamellae, as is usual in Cyathophyllum, and the 

 inclosed vesiculose spaces are somewhat larger. The broad central 

 area of the polyp cells is formed of high, projecting, conical dia- 

 phragms, one incasing the other, and crested on the surface by the 

 central ends of the radial lamellae. The apertural septal fovea 

 well developed, 



CLISIOPHYLLUM ONEIDAENSE, Billings. 



Conico-cylindrical, sometimes elliptically compressed polyparia, 

 annulated by numerous transverse wrinkles and intermediate linear 

 constrictions. The stems are frequently flexuose ; their width is 

 from three to five centimeters, by a length of sometimes over one 

 foot in cylindrical specimens ; the conical cells are shorter, by a 

 diameter equal to that of the former. The basal ends of the larger 

 stems often, for some length, grow in the form of narrow cylindrical 

 pedicles, the surface of which is ornamented with numerous stout 

 spinulose projections, which also extend, but rarely, for some dis- 

 tance higher over the upper, more dilating portions of the stems. 

 The calyces are spacious, with steep side walls, terminating with 

 erect or only slightly expatiated margins. Lamellae near the 

 calycinal margins of alternately larger and smaller size ; further 

 down the sides the lamellae are all of one size ; the smaller inter- 

 calated ones remain confined to the outer margin. A conspicuous 

 septal fovea interrupts the cycle of the lamellar crests, causing a 



