1867.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 355 



fathoms. It is not recorded from Bermuda by Mr. Qiielch in bis re- 

 port oil tbe Challenger reef-corals. 



2. Porites Branneri, uew species. 



(Plate XIX, fig. 2.) 



Corallum small, either incrusting, more or less convex, or siibglobular 

 in shape, generally irregular, but with an even surface, and without 

 defined protuberances or branches of any kind. The cells are very 

 sunill, shallow to moderately deep, without columella but with prominent 

 pali. The corallum is usually attached by the entire base, and may be 

 slightly constricted or expanded at the margins, but the Litter are 

 sometimes free in places for a slight width, the under surface where 

 exposed being provided with a thick epitheca, which is strongly wrinkled 

 concentrically. Xone of the specimens are relatively thin, though some 

 are nearly flat on top. One of the largest of the iucrustiug forms 

 measures about 50 by 35 by 7.5"'™ thick in the niiddle, while one of sub- 

 globular shape is about Qo^^^'^^ in diameter. 



The structure is everywhere very loose and open, especially near the 

 surface, the processes sometimes becoming more thickened below, but 

 always with large perforations. The cells are small, remarkably uni- 

 form in size in each specimen, and not varying much in the entire 

 series examnied ; .75 to 1"''" in diameter, polygonal, separated by thin 

 walls, and Avith moderately thick septa which vary more or less in the 

 different specimens. In some cases the cells are entirely superficial 

 near the margins, but usually they are moderately deep and of the 

 same diameter at the base as at the top. The processes entering into 

 their structure are generally more or less strongly echinulate, being 

 armed with very small, acute spinules, giving the interior a much 

 roughened appearance. Columella absent, bottom of cell usually i)er- 

 forated, but sometimes more or less filled in. Pali 4 to C, generally 5, 

 in number, regularly placed, very prominent, echinulate, varying with 

 the thickness of the septa from slender to moderately stout ; in the 

 deeper cells they extend about half way from the bottom to the top, but 

 in the shallower ones they often reach to the surface. The septa are 

 twelve in number, and vary in thickness and width ; they are unequal 

 in width in the same cell and generally extend from one-half to two- 

 thirds the distance from the wall to the pali, but are often much nar- 

 rower. Above the base each consists of one to three disconnected pro- 

 cesses, more or less resembling the pali in appearance, and projecting 

 inward from a narrow vertical ridge upon the wall. In the bottom of 

 the cell, 8 to 10 of the septa meet in the middle, generally first uniting 

 in pairs, and afterwards becoming more or less connected together by 

 processes which inclose the small central cavity. The upper edges of 

 the walls are serrate, caused by the upward extension of the septa in 

 the form of irregular processes, which are generally echinulate, though 

 sometimes nearly smooth. 



