TRIBE II. CARYOPHYLLACEA. 355 



Other errors have arisen from regarding, too implicitly, external 

 forms, in drawing out generic distinctions. Thus the genera Litho- 

 dendron and Columnaria, as employed, include species which are 

 true Cyathophylla ; and some allied species have been referred to the 

 genus Caryophyllia (Cladocora of Ehrenberg), although differing 

 totally from them, and all others of the Caryophyllidse, in their trans- 

 verse structure. 



The following are the genera of this family, with their characters. 

 In presenting this review of them, the author is aware that the subject 

 requires much farther study before its difficulties will be wholly 

 removed. 



We may subdivide them into the following groups. 



1. Those with the cross septa transverse or but little oblique; some- 

 times nearly or quite obsolete. Includes the genera Cyathophyllum, 

 Calophyllum, Amplexus, Caninia, Acervularia, Arachriophyllum, 

 Cystiophyllum. 



2. Those with the septa very oblique upward, and converging to a 

 central line, with sometimes a distinct axis. Includes the genera 

 Clisiophyllum, Michelinia, Columnaria, and Sarcinula. 



I. SEPTIS TRANSVERSIS RECTIS AUT PAULUM OBLIQUIS, INTEHDUM OBSOLETIS. 



GENUS I. CYATHOPHYLLUM. 



CyathophylKdce simpttcissimce, ramosce, aut glomerate^. Corallum medio 

 interno transversl septatum ; cellis concavis, regulariter stellatis, in- 

 termediis dissepimentis numerosis lamellas conjungentibus, itaque late- 

 rum texturd angulate cellulosd. 



Quite simple, ramose or glomerate. Corallum within transversely 

 septate ; cells concave, regularly stellate ; numerous intermediate 

 dissepiments uniting the lamellae, and the outer portions of the 

 corallum of a polyp consequently angularly cellular. 



The type of this genus is the Cyathophyllum dianthus.* The texture 



* See Murchison's Silurian System, pi. 16, figs. 12, 12 b ; also figs. 9, 10, and 11 a. 



