386 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



more specific information. The latter specimen has corallites with 

 somewhat larger diameter, as much as 7.5, than those of typical 

 specimens, diameter 4.5 to 5 mm., in that respect more closely 

 resembling var. endothecata, but there are no or only a few small 

 costae between the large ones, and the septal characters are more 

 similar to those of var. cylindrica. 



Costa Rica "Colline en demolition", Port Limon,.No. 669, col- 

 lection of H. Pittier. The specimens from Port Limon consist of 

 two isolated corallites, which so closely resemble those of the type 

 of var. cylindrica as not to need comment. Except in size, they are 

 very similar to var. endothecata. 



7. ORBICELLA APERTA (Verrill). 



Plate 89, fig. 3. 



1868. Heliastraea aperta Verrill, Conn. Acad. Arts and Sci. Trans., vol. 1, p. 356. 

 1902. Orbicella aperta Verrill, Conn. Acad. Arts and Sci. Trans., vol. 2, p. 103, 

 pi. 33, figs. 1, la. 



This species is especially characterized by having the principal 

 septa, that is, those of the first, second, and third cycles, all of which 

 ordinarily reach the columella, taller and thinner than is usual in 

 0. cavernosa. At one time I was inclined to consider it only a variety 

 of Orbicella cavernosa, but comparisons of large suites of 0. cavernosa 

 from Florida and the West Indies with a good suite of 0. aperta 

 from Brazil shows persistently recognizable differences. 



Localities. — Abrolhos reefs, Bay of Bahia, and Island of Itaparica, 

 Brazil. 



8. ORBICELLA BAINBRIDGENSIS, new species. 



Plate 90, figs. 1, la, 16, lc. 



In growth form, general aspect of the corallum, and size of calices 

 similar to Orbicella cavernosa. 



Calices 6 to 7 mm. in diameter; walls slope from calicular margins 

 to bottom of intercorallite areas; protuberant about 2 mm.; distance 

 apart from 1.5 to 3.5 mm. 



Costae subequal, relatively thick, rather low, beaded on the 

 edges, correspond to all septa, meet in the intercorallite depression. 



Septa in nearly four complete cycles, 10 to 12 septa, i. e., the 

 primaries and most or all of the sceondaries are thicker than the 

 other septa, these and in some calices a variable number of tertiaries 

 extend to the columella. Usually the tertiary septa do not reach 

 the columella, and the quaternaries are still shorter. The septa are 

 distinctly of three sizes, even where the tertiaries reach the columella 

 they are thinner than the members of the lower cycles. Septal 

 margins dentate; distinct, rather wide, erect paliform lobes usual 

 on the inner ends of the primaries and secondaries and in- places 

 on the tertiaries; on some septa instead of paliform lobes there are 



