368 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



Variation No. 3 (pi. 82, fig. 2) is represented by a single specimen. 

 The corallum is discoid, lower surface flat, upper surface convex, some 

 irregularities. Greater diameter, 22.7 cm., lesser, 19.2 cm; thickness 

 in the center about 5 cm., on the edge, 3 cm. 



Calices with elevated margins and crowded together, the different 

 corallite walls almost contiguous; margins of primary and secondary 

 septa decidedly exsert. Diameter of calices about 2.75 mm. 



The distinguishing characters of this variation are its discoid form, 

 its crowded calicos, its decidedly exsert septal margins. 



Locality. — Fort Taylor, Key West, Florida. 



Variation No. 4 (pi. 82, figs. 1, la) is represented by the speci- 

 mens that I have described from Mayaguez, Porto Rico, in my 

 "Stony corals of the Porto Rican waters." 1 The following descrip- 

 tion is based on them: 



The corallum forms ascending masses; the largest specimen is 

 about 20 cm. tall; diameter above flared -out base about 13.5 cm. 

 The base of each specimen is considerably produced as a wide, free 

 edge invested below by epitheca. 



Calices with very slightly or only moderately elevated margins, 

 diameter measured between thecal summits, from 3.25 to 4 mm. ; 

 rather shallow; distance apart, from a thin dividing edge to 2.5 

 mm.; about 1.5 mm. is probably the average. Thin costae moder- 

 ately prominent, subequal, or alternating in size, correspond to all 

 septa; those from one calice extend across the intercorallite spaces 

 and meet those from the adjacent calices. 



Septa thin, 24 to 28 in number, one-half of them extend from the 

 wall to the columella, and have decidedly exsert margins ; the other 

 half are not so tall and are short, their inner ends free. 



Endotheca and exotheca as in the typical specimens, except that 

 they are more delicate. 



These differ from typical specimens by their much lighter texture, 

 which, of course, is determined by their thinner skeletal structures, 

 the wide, flaring, free edges of the base, and their larger calices. 

 The calices overlap in size those of variation No. 2, otherwise I 

 should consider the specimens as representing a distinct species. 



Variation No. 5 (pi. 83, figs. 1, 3, 3a). — Orbicella hispidula Verrill. 2 

 The following is the original description : 



Coral an incrusting mass over 125 mm. across, and from 5 to 20 mm. thick. The 

 texture is rather solid and heavy, there being much solid exotheca between the 

 calicles, which are rather far apart, the interspaces being mostly equal to, and often 

 exceeding, their diameter. 



The calicles are round, regularly stellate, a little prominent, with swollen, sloping, 

 costate rims much as in those of 0. annularis, which they resemble in size, though 

 distinctly larger. The septa are in three very regular cycles; the twelve principal 



i Bull. U. S. Pish Commission for 1900, vol. 2, p. 301, pis. 6, 7, 1901. 



2 Conn. Acad. Arts and Sci. Trans., vol. 11, pp. 100, pi. 15, figs. 3, 3a, 3&. 



