332 THE PROCEEDINGS OF THE LINNEAN SOCIETY 



principal septa slightly, or not perforate ; 2nd, Poritidce ; en- 

 tirely composed of reticular sclerenchyma ; septa represented 

 by little bars or processes. 



The Madreporidse are again subdivided into three families : 

 1. Eupsammince ; no independant coenenchyma. 2. Madreporince ; 

 coenenchyma abundant, six principal septa, two of which are 

 much greater than the rest. 3. Turbinarinee ; septa six, equally 



developed. 



First Fam., Eupsammike. 



Septa well developed and forming many cycles ; primaries 

 equal but the last cycle bent towards the preceding order, so 

 that the calice has not the radiate appearance of most corals ; 

 wall formed of distant vertical sclerenchymatous nodules, united 

 only at their points of contact so as to leave perforations which 

 occasionally become obliterated below only. They are simple or 

 compound corals ; the corallites nearly always cylindro-conical 

 without exotheca or peritheca ; wall feebly costulate, scarcely ever 

 with a complete epitheca,* the tissue being shagreened or velvetty 

 in aspect; cycles 4, 5, rarely the rudiments of a 6th; the last 

 cycle of whatever number, never forms straight rays but bent 

 according to a simple law, thus : — If it be of four cycles, the fourth 

 order diverges from the primary, and the fifth order from the 

 secondary, until they meet or nearly meet in front of the tertiary, 

 with which they are intimately united below. If there are five 

 cycles it is the 6th, 7th, 8th, and 9th orders which diverge. Each 

 half of the system will then resemble an entire system of four 

 cycles ; on one side the 6th system diverges from its adjoining 

 primary, and the 8th from the tertiary, to unite together, and 

 with the fourth which is between them ; on the other side the 7th 

 diverges from the secondary, and the 9th from the tertiary, to 

 unite with the 5th which they bound on the left and right. 

 Sometimes the penultimate bends towards the tertiaries and the 

 tertiaries towards the secondaries, so that the primary alone is 

 free ; this peculiarity though always present is feebly manifest in 

 some genera such as Leptopsammia, Endopsammia, and Dendro- 



* Dandrophyllia epithecata. Duncan, a fossil of Tasmania, is a solitary exception. 



