118 EOCENE AND LOWER OLIGOCENE CORAL FAUNAS. 



The dense coenenchyma which is laid down on the stock is of spe- 

 cial interest This is deposited in layers parallel to the surface of the stock, 

 and is striate perpendicularly thereto. This coenenchyma is composed of 

 minute calcareous bars which break into small blocks. As yet I have been 

 unable to find calcification centers or nuclei from which the bars radiate. 

 In some places a faintly radiate arrangement could be distinguished. I 

 could not even make out the calcification centers in the septa where we 

 know they exist, so there may have been the usual radiate structure in the 

 ccenenchyma also. The interseptal loculi are filled, as Hinde has repre- 

 sented to be the case in Septastrsea. 



OcuLiNA MississiPPiENSis (Conrad). 

 PI. KI, all figs. 



1847. Madrepora missis sippiensis Conrad. Proc. Acad. Nat. Sci. Phila., Vol. Ill, p. 296. 

 184:8. Madrepora mississi2>piensis Courad. Jour. Acad. Nat. Sci. Pliila., 2d ser., Vol. I, 



p. 127, 1^1. xlii, tig. 22. 

 Lesueur Planches incdites, No. 5, fig. 15 aud perhaps also figs. 12 and 13 (fide 



Milne-Edwards and Ilaime). 

 1850. OcuUna aiiierivuna Milne-Edwards and Haime. Annales sci. nat., 3d ser., Vol. 



XIII. p. 70. 

 1857. Oculina americana Milne-Edwards and Ilaime. Hist. Nat. des Corall., Vol. II, 



p. 108. 

 18G1. Oculina americana de Fromentel. Introd. a I'lStude des Polyp, foss., p. 170. 

 ISGG. Dendrophyllia mississippiensis Courad. Check List, p. 2G. 



•The following is a translation of Milne-Edwards and Haiiue's original 

 description of Oculina americana: 



Branches cylindrical, calices circular, considerably crowded together, disposed 

 according to rather regular spirals, terminatiug in distinct tubular mamelons opening- 

 upward. The terminal calice is in general larger than the others. Costal striaj not 

 very pronounced, very fine, tlexuous, slightly unequal. Fossa of the calice not deep. 

 Columella and pali moderately developed. Septa in three complete cycles; in addition 

 in one of the halves of two systems, one observes constantly septa of a fourth cycle, 

 and the tertiaries comprehended between these attain a development almost equal to 

 that of the secondaries, and coalesce near the internal margin of the secondaries. 

 These septa are crowded together and are slightly exsert. 



We have observed only isolated branches about 2 centimeters in size; the 

 individuals are or 7 millimeters at their base, only three at the calice. 



Fossil from the middle tertiary of the Walnut Hills, on the banks of the 

 Mississippi: 



Coll. Mus. (Lesueur).' 



' Milnp-Edwarda and Haime, Annales soi. nat., 3il ser., Vol. XIII, 1857, ]). 70. 



