464: G. M. Ehlers — New Species of Tetracoralla. 



siderable width except for its partial covering by tabulae, 

 is a small, irregular wedge-shaped protuberance, which is 

 shown on fig. 3 above / and to the right of a deep, narrow 

 and much elongated depression. The thin covering of 

 the protuberance consists of a folded portion of the 

 incomplete and much fractured tabula indicated as t 2 , fig. 

 3 ; the space beneath the folded portion of tabula is more 

 or less filled with colorless, crystalline quartz. A nar- 

 row, obscure band of light-gray, crystalline quartz, which 

 is in contact with the inner side of the tabula on the left 

 side of the protuberance, extends from the wall of the 

 corallum to the inner surface of the tabula above. This 

 strip of gray quartz may represent the cardinal septum 

 for the reason that it occupies the position of this septum 

 in the central part of the fossula. Further evidence that 

 the band of quartz may represent the cardinal septum is 

 indicated by its apparent continuity with the base of this 

 septum, a small part of which seems to be split by a 

 break (b, fig. 2) in the wall of the corallum. A counter 

 septum (c, fig. 3) and two alar septa (a, fig. 3) are 

 readily distinguishable in the calyx and on the lower side 

 of the specimen. The secondary septa are lamelliform 

 and show no denticulations on their inner edges. Forty- 

 four of these septa are shown in the calyx, eleven occur- 

 ring in each quadrant. A septum is doubtfully indicated 

 on each side of the ill-defined cardinal septum. On the 

 lower side of the specimen, eleven septa also occur 

 between the counter and each alar septum but only ten 

 between each alar septum and the cardinal one. The 

 two or four extra septa, shown in the calyx between the 

 alar septa and the center of the fossula, are inserted at a 

 point above the lower surface of the specimen. Midway 

 between the secondary septa are very low, tertiary septa, 

 each of which bears a single row of sharply pointed den- 

 ticulations upon its inner margin (see fig. 3). Between 

 these denticulate septa and the lamelliform septa are 

 very low, obscure septal ridges, representing quaternary 

 septa. 



The central part of the calyx and the interior of the 

 corallum below it are occupied by wide, slightly concave 

 tabulae, which curve sharply down between the lamelli- 

 form septa and unite with the wall of the corallum. Two 

 nearly complete tabulae are shown in the specimen (see t 

 and t 1 , figs. 2 and 3). Overlying the upper one in the 



