BULLETIN oil, L'NITED STATF..S NATIONAL MTSEUM. 1'J7 



The folic jwiiifr iU-count of this species is based upon the detailed study of 100 

 specimens. The uinoiiiit of variution is enormous luid hewilderinij. The tj'pe 

 specimen will be described Hrst; subsequently the diffeient vaiiiitions will l)e con- 

 sidered and their interconnection indicated. 



Dana's figured type is preserved in the United States National Museum, and on 

 it the followino; description is based (Plate LXXXI. ti^'s. 1. 1*/, 1/)): 



The corallum consists of compressed, ascendiiiir columns, coalesciiii;' interiorly, 

 terminated by short, truncated or obtusely rounded free ends. The two views on 

 Plate LXXXI will ii-i\'i' an i<lea of both the form and size, in one place there is a 

 younger layer growing over a lower dead portion of the corallum; usuall}', however, 

 the growtli is continiums. 



Calices polygt)ual: usual diameter. I.."* mm.; shallow or of moderate depth. 

 Walls distinct, contituioiis. perforate, membraniform, witii acute edges. The mem- 

 braniform walls, with tlicii- elevated, sharj) edges, constitute one of the striking 

 features of the specimen. Within each calice is u periphcridly disposed ring of 

 s\'napticula, usually separated from the wall by short poll ions of the interseptal 

 loculi, sometimes, however, fused to it a])j)arently by secouilary thickening. The 

 "trimurate" condition is fi-e(|uently represented. 



Each septum between tlii' palus and w;dl normally has one trabi'cula, which ter- 

 minates in a moderately prominent septal granule, detached from the wall, and stand- 

 ing either on the inner edge of or above the peripheral ring of synapticula. The 

 septal faces are granulated: the intersepttd loculi wide above, narrow below, divided 

 into two parts by the outer synaptiiulai' ring. 



The palar formula is comiili'te, but because of the damaged condition of the 

 coi-allum. a detailed description is not possible. There is a ring of palar -ynapticula. 



The columella is a narrow lamella lying in the plane of the two directive septa, 

 joined to these and the lateral pairs t)y six radii. The whole colunudla tangle may be 

 considerably compacted. 



The foregoing description of the calices and the calicular structures is based on 

 the lateral calices. which show the various skeletal elements in their typical develop- 

 ment. There is some variation from the typical calices l)oth on the sununits and 

 near the bas(>. 



The summits may bear calices similar to the lateral ones, or they may l>e com- 

 posed of a spongy reticulum, the corallites iipon casual observation appearing not to 

 be differentiateil. Closer study shows that they are detinite, and that the trabecular 

 structure is in plan identical with that of the lateral calices; the various skeletal 

 elements are thinner, the walls arc not elevated, causing the calices to be superficial, 

 the synapticular I'ings are not complete, and there is greater indetiniteness in the 

 columella tangle. However, all the trabecular elements are present in the reticulum 

 and can be distinguished, but, being immature, they have not assumed the detinite 

 arrangement of those ii\ the lateral corallites. 



On the lower j)orlion of the corallum the calices arc \cry shallow; frecpiently 

 there are two dentjitions on a septal margin between a palus and the wall; usually, 

 however, there seems to be only one septal trabecida. The upper edge of the \\all 

 consists of a row of more or less connected erect, frosted rods. Interseptal loculi 

 narrow, with very irregular outlines. 



