﻿GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 433 



a genus, designating as the type-speoies 0. plana M. Edwards and 

 Haime, which is a new name for Agaricia sommeringii Michelin ^ 

 (not Goldfuss), from the middle Oohte of Mecrin and HannonviUe 

 (Meuse) . A part of the description of 0. plana is as follows : ' ' Quelques 

 collines mmces et pen saillantes entre lesquelles on voit souvent 

 plusieurs series de centres caUciiiaux. Ceux-ci sont bien distincts et 

 pen profonds." 



The multiple series of calices between collines and the very dis- 

 tinct calicinal centers appear to be vahd generic differences. Further- 

 more hi the distmct calices of Pironastraea the columella is false but 

 clearly papillary, whereas in Orosens the columella is rudimentary. 

 There may be additional differences in septa] structure not ascertain- 

 able from the short description of the type-species of Oroseris. 



Pironastraea differs from Pacliyseris by its more distinct calicinal 

 centers; but apparently it is the ancestor of the latter genus. 



PIRONASTRAEA ANGUILLENSIS, new species. 



Plate 111, figs. 1, la, 16; plate 112, figs. 1, la. 



Corallum forming plates as much as nearly 5 cm. thick, and more 

 than 12 cm. across. Width of valleys measured between colhnes 

 summits from 2.5 to 5.5 mm., about 4 mm. usual; height of collines 

 above the bottom of the axial furrow or of the columella pit about 

 3 mm. Distance between distinct calicinal centers ranges from 3 

 to 4 mm. 



Septa numerous, from 38 to 45 in fully developed calices, most of 

 them extend to the axis, some groupir.g m 3's at the cahcular ends. 

 On a septum 2 mm. long about 10 crowded, knot like dentations. 

 Septo-costae equal, crowded, 18 were counted within 5 mm. 



The columella fossa, where the calicinal centers are distinct, is a 

 small pit, less than 0.5 mm. in diameter. 



Synapticulae abmidant, crowded, 7 or more to an mterseptal 

 loculus. 



Locality and occurrence. — Anguilla, stations 6893, 6894, 6966, 

 Crocus Bay, T. W. Vaughan collector. A specimen from station 

 6966 was obtamed m place between 30 and 50 feet above the base 

 of the bluff on the west side of Crocus Bay. 



Porto Rico, Lares Road, zone C, coDected by Mr, Bela Hubbard 

 of the New York Academy of Sciences Porto Rico Expedition. 



Type— No. 325174, U.S.N.M., pi. Ill, figs. 1, la, 16. 



Paratype.—^o. 325175 U.S.N.M., pi. 112, figs. 1, la. 



1 Iconograph zoophytol., p. 105, pi. 23, flg. 2, 1843. 



