376 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



mary septa largest. Columella rudimentary. Endotheca abundant. Diameter of 

 calice, with costae, one-fifth inch [5 mm.]. 



The deficient columella is the only point in which this species differs from Madre- 

 pora limbata Goldfuss, which has been determined by Milne Edwards to be a Stylina. 



From the yellow shale of San Domingo. Coll. Geol. Soc. 



Original description of Plesiastraea ramea: J 



Corallum in gibbous masses or more or less cylindrical processes with irregular 

 swellings. Calices distant, very slightly exsert, circular, and unequal in size. 

 Septa thick at the wall, thin internally, unequal in size, according to the 

 orders; finely dentate above, but sparely granular laterally. In six systems of three 

 cycles, with occasionally an additional order in one-half of a system. Pali very 

 small. Columella lax, papillated, and small. Fossa moderately deep. Costae well 

 developed, subequal, and marked by three or four dentate projections; they are evi- 

 dently covered with a fine epitheca, which is not granular; where the epitheca is worn 

 the costae are seen to be smaller, the tertiary being much smaller than the others; all 

 project, however. Exotheca moderately developed and often becoming indurated. 

 Endothecal dissepiments fragile, but horizontal and frequent. Height, some inches; 

 diameter of branches 1 inch, more or less; diameter of corallites four-thirtieths inch 

 [3.3 mm.]; distance between corallites about one-tenth inch [2.5 mm.]. 



From the silt of the Sandstone plain, San Domingo. Coll. Geol. Soc. 



I examined Duncan's types of Phyllocoenia limbata and Plesiastraea 

 ramea in the Geological Society of London and made a note that the 

 latter, except that its septa are broken down and the calices have a 

 hollowed-out appearance, is the same as the former. 



In my Some fossil Corals from the elevated Reefs of Curacao,. 

 Arube, and Bonaire, and my Stony Corals of the Porto Eican 

 waters, I placed in the synonymy of Orbicella acropora { = 0. 

 annularis), the three names of Duncan, cited above, considering the 

 specimens to which they were applied as growth forms of that species. 

 More detailed studies, subsequently made, have led me to believe 

 that I was mistaken in that course. This coral is very similar to 0. 

 annularis. However, there appear to be two constant differences — 

 namely, the primary septa within the calices are uniformly thicker 

 and usually longer than the secondaries (this lesser development of 

 the secondaries is not occasional as in 0. annularis but constant) and 

 small, but distinctly developed, pali occur before the primary and 

 secondary septa. 



I have for study one specimen from Duncan's original material, 

 labeled Plesiastraea ramea Duncan, No. 155273, U.S.N.M., kindly 

 sent to the United States National Museum by the authorities of the 

 Geological Society of London (see pi. 85, figs. 1, la); 10 specimens 

 belonging to the Museum of Comparative Zoology, 4 specimens 

 collected by Miss C. J. Maury in Santo Domingo, and material 

 obtained by myself near Santiago, Cuba. The first specimen is not 

 in very good condition for study, and does not fit Duncan's descrip- 

 tion well. The Museum of Comparative Zoology specimens, however, 



1 Geol. Soc. London. Quart. Jour., vol. 19, 1863, p. 421. 



