1867.] DTJNCAN AVEST-INDIAN COKALS. 21 



and internal walls. Reproduction by gemmation in the coenenchymal 

 space. 



DirLoccENiA MONiTOK, spcc. nov. PI. I. figs. 3 a~3 c. 



The corallites are crowded, and either hexagonal or pentagonal, 

 and they are rarely four-sided. The inner wall is more or less cir- 

 cular, and the coenenchymal space varies in size and in the amount 

 of eudotheca. The external wall is stout, wavy, imperforate, and 

 slightly higher than the internal. The septa arise from the inner 

 wall, and very rarely from the outer, or from the coenenchymal 

 space. The lamina3 are linear, straight, wide apart, and do not all 

 project to the columella, but one septum often does. Minute septa 

 appear here and there between the others, which are subequal. The 

 septal number is variable. In a small corallite there are 15 large 

 septa and 3 small ; in a larger, 13 large and 9 rudimentary septa ; 

 in other corallites 19 large and 5 small septa, 14 and 4, and 14 and 

 10 septa. 



There are no costee. The columella is lamellar and flat, but very 

 distinct, and is often joined to one or more septa. 



The endothcca between the walls is inclined and vesicular, and 

 rather abundant, and that within the internal wall and between the 

 septa is very sparely developed. 



Diameter of largest corallites ^ inch, the coenenchymal space 

 being about -^V iiich wide. 



The mineralization is siliceous ; and the specimen is in the British 

 Museum, among the Antiguan corals. 



This is a very remarkable genus ; for it is, as it were, a Litho^ 

 strotion of the Palseozoic Coral-fauna without tabulae. There is 

 nothing like it known ; and the lingering of the old type in associa- 

 tion with vesicular endotheca and an irregular septal arrangement 

 which is certainly not hexameral is very interesting and sug- 



POCILLOPORA TENUIS, SpOC. UOV. PI. I. figS. 5 rt-5 C. 



The corallum is large ; but the amount of intercoraUite coenen- 

 chyma is small everywhere, whilst it barely exists in some parts. 

 The tabulse are very delicate, rather and unequally close, and are often 

 marked with a projection — the columella. The intertabular spaces 

 do not fill up with coral tissue. The septa are small, very distinct, 

 and are usually twelve in number; but in some calicos there are a 

 few rudimentary septa. 



The corallites are usually crowded, and six occupy about | inch. 



Log. Antigua (Coll. Erit. Mus.). 



The delicate tabular and the patency of the intertabular spaces 

 distinguish this species. It is interesting to observe in the same 

 specimen portions without coenenchyma and portions with it, espe- 

 cially as these two conditions are considered generic in Palaeozoic 

 corals ! Pocillopora crassoramosa, nobis, has much coenenchyma ; 

 and so has P. Jenkinsi, Eeuss, its nearest ally, from Java. 



