58 BRITISH FOSSIL CORALS 



Family— ASTR^IDJE. 



Division — Lithophyllace^ simplices. 



Genus — Montli valtia . 



The MontlivalticB from Fenny Compton, Honeybourne, and Cheltenham, belong to 

 several species, and two of these are singularly polymorphic. Shape has not very much 

 to do with the specific diagnosis of some recent simple Corals, and it is necessary to assert 

 this in collecting under one fossil species Corals of very diverse external forms. Singularly 

 enough, the Liassic MontlivalticB from the Zone of Ammonites raricostatus are common 

 and are extraordinarily well preserved, although a few years ago a Liassic Coral was 

 excessively rare. Even the ornamentation upon the dentations of the septa is pre- 

 served, and the longitudinal striations of the epitheca also. The Fenny Compton 

 Coral-bed contains specimens of the species of all sizes, and this is the case with the 

 deposits containing the so-called Thecocyathus rugosus, Wright, at Honeybourne and 

 Cheltenham. At Pebworth the Fenny Compton species are not found in a dark blue 

 matrix, but in a white deposit ; moreover, the specimens are usually worn, and they appear 

 to have grown under less favorable conditions than the others. 



Thecocyathus rugosus is referable to a group of forms specimens of which are very 

 common ; it does not belong, however, to the same family that contains the Thecocyathi. 

 Dr. Wright gave the species a name in his MS,, but the description and diagnosis have 

 never been published. The Corals have been associated so long with the name of Dr. Wright, 

 that it is just to append his name to the species. 



1. Montlivaltia rugosa, Duncan and Wright. PI. XIV, figs. 1, 2, 3; PI. XV, 

 figs. 14, 16, 17 ; PI. XVI, figs. 5—15. 



Thecocyathus rugosus, Wright, MS. 



The corallum is very variable in its shape ; it may be tall, conico-cylindrical, and curved, 

 sub-turbinate and curved, short and cylindrical, short and turbinate and curved, or 

 straight. It is pedunculate, and the scar by which it adhered to foreign substances, such 

 as shells, is large and oval, or small and very irregular in shape. 



The epitheca is stout and identified with the wall ; it is strongly ridged transversely 

 and folded as well as grooved. It is rarely marked by longitudinal lines, and is usuaUy 

 deficient in ornamentation. When the epitheca is worn, the external ends of the septa are 

 seen like costae, and the oblique external terminations of the endotheca are very apparent, 

 sometimes having a herring-bone pattern. Young corallites are often adherent to the 



