ASTROCiENIA. 69 



DENDROGYEA EiirbCx. 



Dendrogyra cylindrus Ehrbg. 



Very rare ; only found occasionally thrown up on the beaches. Fine 

 specimens in the Museum received from Mr. Duchassaing, of Guada- 

 loupe, show very distinctly the mode of growth of the prongs arising 

 from large hemispherical masses. 



Subfamily ASTR^INJE M.-Edw, & H. 

 ASTROC.ENIA M.-Edw. & H. 



This genus is known only from the oolitic, cretaceous, and tertiary 

 formations. It was placed by Milne-Edwards and Haime among the 

 StylinaceaB, on account of its supposed entire septa. Reuss, who had 

 better preserved specimens, has shown that they are denticulated. I 

 have found this character strongly marked in some specimens of 

 A. reticulata from Gosau, particularly in some calicles placed in a cavity 

 where they had been protected from abrasion. 



Heller has referred to this genus a small coral discovered by him in 

 the Adriatic. From the description and figure, however, it would seem 

 to be a Madracis, as it has ten equal septa. 



Astrocaenia pectinata Pourt. 



Corallum small ; incrusting. Calicles crowded ; wall forming a sharp 

 ridge ; costa) spinous, gen-erally not confluent. Fossa deep. Septa in 

 two cycles, not very different from each other ; six complete systems ; 

 the lamella of the septa rudimentary, but extending into long spines, 

 which join the columella in the lower parts. Columella rather stout, 

 conical, hollow, free to a considerable depth. Dissepiments not numer- 

 ous. Growth by lateral gemmation. Diameter of calicles 1.5 mm. 



On base of a Madrcpora iirolifera, in Mus. Comp. Zool. 



