28 PEOF. p, MARTIN Duncan's retiston of the 



eulate shape, the barely exsert numerous septa without pali, and 

 the essential fasciculate columella. It is not separable from Gono- 

 trochus ; and one of the species of this genus, now merged into 

 Oeratotrochus, has in some of its individuals stereoplasma joining 

 the septa near the margin, and a bark -like epitheca. The reasons 

 for joining ConotrocJius and Geratotrochus are evident ; and I 

 place Moseley's interesting form, so beautifully figured by him, 

 in Geratotrochus, Ed. & H. 



VI. Alliance DISCOCYATHOIDA. 



Simple Turbinolidse, discoid in shape, not increasing much in height 

 with growth. Free or not. With or without pali in one crown. Colu- 

 mella variable ; epitheca also. 



Genus Discocyathus, Ed. & H. 



Genus Brachytrochus, Duncan. 



Genus Sabinotrochus, Duncan. 



Genus Stephanotrochus, Moseley. 



Genus Discotrochus, Ed. & H. 



Genus Cyclocyathus, Ed. &H. 



Genus Brachycyathus, Ed. &H. 



Genus Anthemiphyllia, Pourtales. 



Genus Fungiacyathus, Sars. 



Genera absorbed : — Paterocyathus, Duch. & Mich. ; Brachy- 

 trochus, lleuss. 



Whilst admitting the necessity of recognizing discoid species 

 of the genus TrochocyatTius, there are still several genera which 

 can hardly come within that genus or its alliance, and which con- 

 tain discoid, low, cup-shaped forms, with and without pali in one 

 row. 



The genera Discocyathus, Gyclocyathus, Discotrochus, Brachy- 

 cyathus, Brachytrochus, Sahinotrochus, and Stephanotrochus form 

 an alliance, the Discocyathoid ; and their very common facies is 

 not interfered with by the fact that one genus has no columella 

 and another a lamellar one, three others having them essential 

 and fasciculate. 



G-enus Discocyathus, MM. Milne-Edwards Sf Jules Raime, 

 Ann. des Sci. Nat. 3^ ser. t. ix. p. 296 (1848). 



The corallum is simple, free, and discoid, with a flat horizontal 

 wall covered with a concentrically folded epitheca. The septa 



