BULLETIN 5',), UNITED STATES NATION.VL MUSEUM. 93 



3. POCILLOPORA MODUMANENSIS. new species. 

 Plate XVII, liiTs. 1, I-. 



Corallum composed of ascending, rather distant, rather wide or almost terete 

 branches; upper surface of colony rounded. The widtli of the upper end of the 

 widest branch is .i" mm.; tiiiekness, between !• and lo mm.: the greater diameter of 

 the upper end of the smallest branch is 14: mm.; les.scr, l-J nun. Surface of tlie 

 l)ranches, witli luunerous, regularly spaced \crrucie. which stand peipendicular to 

 the surface of the branches, near the upper ends somewliat l)ut not greatly inclined, 

 and are strikingh- uniform in size. They average about 2 mm. in diameter at the 

 base and are about 2 mm. in height, the diameter decreasing toward the rounded or 

 subacute apices. The distance l)etween them from sligiitly less than '^ mm. to 3..") mm. 

 The summits of the branches may or may not be verrucose. 



Calices moderately deep, on the sides of the branches rather small, about 0.7 mm. 

 in diameter, crowded among the bases of the verruca', usually less than their diameter 

 apart; they may be separated by only a thin wall, or the wall may .sometimes be as 

 much as 0.!* mm. thick. On the ends of the branches the diameter is often as much 

 as 1 mm., in some instiuices it is more; here the walls are very thin. The calices on 

 the verructe are separated by narrow walls. The septa, except on the summits of 

 the branches, are well developed, 12 in number, usually distinctly divided into two 

 cj'cles. One septum is elongate and connects with the columella. Although the 

 septa are distinct and, excepting the elongated one, are narrow above; their edges 

 are dentate, the dentations, small spines, projecting horizontally inward. Columella 

 prominent, terminated I)}' a style. 



The broken lower end of the specimen shows a compact ccenenchjmia, and as the 

 corallite cavities are tilled b\' internal deposit, the substance of the corallum is almost 

 as compact as in P. ligulata; but in cross sections of branches higher up, the sei'ies of 

 tabuliv may continue almost to the outer surface of the branch, a tabula sometimes 

 forming the bottom of a calice. On the surface of the coenencln'ma, on the sides of 

 the branches, are single, double, or treble rows of granulations between the calices, 

 depending upon thcii- distance apart. The granulations are small in diameter at the 

 base, rather tall and pointed. Around the edges of the calices on the verrucie there 

 are rather frequently tall spiniform granulations or thin plates. 



Local if I/. — Vicinity of ^lodu Mann or Bird Island, Station 41 G'.'; depth, 21 to 22 

 fathoms; l)ottom, coral; temperature, 78.3-; 1 specimen and another fragment. 



Type.— C&t. No. 20984, U.S.N.M. 



lieni/irl'x. — This species is separated fiom P. iiieandrhiu Dana by pos.sessing dis- 

 tinctly developed .septa and a styliform columella; from the /'. Ihjuliito by the regular 

 size and uniform distribution of the verruca', which arc nearly perpendicular or only 

 slightly inclined to the surface of the branch; they aic not appressed and do not tend 

 to form carina'. The calices are moi'c crowded, and the corallum is lighter. /'. 

 ■niodumanensis is more closely related to /'. liijuhifii than to any of the other species 

 of the genus from the Hawaiian Islands. 



The following species from the South Pacific and Indian oceans are related: P. 

 pJicata Dana, I\ eydouxi Milne Edwards and Haime, /*. elongata Dana (of which 

 P. eydouxi is probabh' a .synonym), /'. coroimfa (Jardiner (also probably a synonym 

 of P. ehinxjatii)s and P. rugosii (Jardiner. H^ach of these presents marked ditl'erences 

 in the verrucie, or in the calicular characters. 



