TRIBE III. MADREPORACEA. 539 



SUBFAMILY III. HELIOPORIN^E. 



Favositidtf polypis spar sis. CoraUi cettis orUculatis non contiguis, radiis 

 angustis. 



Favositidse, with scattered polyps; cells of the corallum circular, not 

 contiguous, rays very narrow. 



GENUS VII. HELIOPORA. BLAINVILLE. 



FavositidcB glomeratce aut ramosce. CoraUi cellis parvulis, incequalibus, 

 remotis, inter stitiis minute cellulosis et penitus suUiliter tubulatis. 



Glomerate or ramose. Corallum with the cells quite small and un- 

 equal, remote, interstices minutely cellular and internally fine 

 tubular. 



The Helioporse occur either as glomerate masses, or lamellar and 

 subramose. They are characterized by their small, unequal, pore-like 

 cells, separated by minutely tubular interstices, each of which tubes 

 opens in a pore at the surface. Only a single recent species has been 

 described ; and, in this, the surface is covered with smooth granules 

 or points; among- which the cells are about a fourth of a line in 

 breadth, and each has a circle of twelve granules around the aperture. 

 The transverse septa are quite distant, It is peculiar also in having a 

 1)1 ue colour internally. This blue colour is of animal origin, and is 

 lost on immersion in nitric acid. 



This genus was instituted, by Blainville, for the Pocillopora c&rulea 

 of Lamarck, and certain allied fossil species. These fossils, though 

 similar, yet differ from the Helioporse, in having the interstices irre- 

 gularly cellular, instead of minute tubular. 



The genus HETEROPORA of Blainville (imperfectly characterized by 

 this author), includes some small branched fossils of cretaceous origin, 

 with "two kinds of pores;" one set being three or four times larger 



