56 BRITISH FOSSIL CORALS 



XV. Corals from the Zone of Ammonites obtusus, Sow. 



Some worn and light-coloured simple Corals of the genus Montlivaltia are found at 

 Pebworth, five miles south-west of Stratford-on-Avon, in abed with Ammonites Sauzeanus, 

 D'Orb., and Ammonites semicostatus. One of the species {Montlivaltia mucronata, Duncan) 

 will be described amongst those of the next zone, in which it is common. The specimens 

 are worn, the calices especially, and all the spines are broken oflF. The columellary space 

 is occasionally occupied by the prominent ends of the principal septa, the laminae having 

 been worn away in their middle course. The longitudinal series of costae are rarely visible, 

 and there are many examples of deformed corallites. 



Family— A STRtEIDtE. 



Division — LlTHOPHYLLACEiE SIMPLICES. 



Genus — Montlivaltia. 

 1. Montlivaltia patula, Duncan. PL XV, figs. 6, 7, 8. 



The corallum is turbinate, depressed, and slightly longer than broad. 



The calice is large, elliptical, very shallow, and open ; its margin is sharp, and the 

 wall shelves very gradually inwards, giving to the calice a very open appearance. 



The septa are unequal and numerous, and the largest are very long and dentate ; the 

 tooth nearest the axial space points inwards and is rounded, and those of the longest 

 septa form an irregular circle around the space. The smallest septa are very rudimentary, 

 but the next in size have, in common with all the others, an internal oval tooth. Ail the 

 septa are delicate, and they are not crowded. There are five cycles of septa in six 

 systems. The primary, secondary, and tertiary are nearly equal in length. The septa are 

 not exsert, but all are lower than the calicular margin. 



Length of the calice x'jths inch. Breadth -ths inch. 



Locality. Walford Hill, Stratford-on-Avon, with Ammonites semicostatus and 

 Ammonites Sauzeanus. In the Collection of R. Tomes, Esq. 



