DESCRIPTIONS OF SPECIES. 147 



The coralluin is either massive or branching. The corallites are 

 circular or slightly elliptical, 1.5 to 2 mm. in diameter. In the axial portion 

 of a branch they are joined directly by their walls, which are not very thick, 

 or by costje. On the surface of this branch, which is about 12 mm. in diam- 

 eter, the corallites are separated by stout, thick walls, from slightly less to 

 slightly more than a millimeter thick. Costne correspond to all septa. The 

 outer surface of the corallum has been eroded; therefore the details of its 

 ornamentation are obliterated. There are three cycles of septa, six systems; 

 the members of the first cycle and usually some or all of the second cycle 

 reach the columella space. The margins are not preserved, but from other 

 characters the inference that they are entire can be drawn. There are no 

 granulations on the septal faces, but, when looked at from above, wing-like 

 expansions can be seen extending outward from the sides of the septa. 

 The inner portions of the septa are transversely ^^ndulated. The septa are 

 decidedly thicker at the wall, and the larger ones are thickened on their 

 inner ends. Endo thecal dissepiments are abundant and well developed; 

 corallite cavity not filling up with secondary deposit. The columella is not 

 "projecting beyond the edges of the septa," as Gabb states. He Avas misled 

 by the weathered condition of most of the calices. In a well-preserved 

 calice no columella can be seen from above, the margins of the larger 

 septa meeting in the axial space. The columella is false, but is usually quite 

 solid and firm, so that in weathered calices it stands out prominently. The 

 calicular fossae are shallow, almost superficial. 



This material is in excellent condition for the study of the microscopic 

 features ; therefore the following notes are made : 



The septa. — In tlic cross section of a corallite, the median dark line of a 

 septum exhibits a row or chain of calcification centers. They are elongate 

 elliptical and are connected with each other in a moniliform manner. The 

 measurement across three very distinct centers Avas 0.09 mm., or tlie dis- 

 tance from one to the next adjacent center is 0.045 mm., but in places they 

 may be more crowded. The measurement at right angles to the above, 

 across a center, is 0.009 mm. The fibro-crystals diverge from the median 

 septal plane toward the center of the corallite at an angle of about 45°. 

 This section is so well preserved that in places one can distinguish the 

 minute growth curves crossing the fibro-crystal. On one side of this septum 

 is a protuberance, in which is a large distinct calcification center. The Ion- 



