134 BRITISH POSSIL CORALS. 



thick epitheca, presenting concentric folds or wrinkles, and a very small central cicatrix. 

 Calice circular, and somewhat convex; fossula shallow and oblong. Scjjta straight, 

 exsert externally, unequally developed, terminated by a strongly denticulated edge, and 

 forming five complete cycla, four of which are well developed ; those of the second cyclum 

 dififer but httle from the primary ones, and are thicker than the others ; those of the fifth 

 cyclum rudimentary. Some denticulations larger than the others, and situated at the inner 

 angle of the principal septa produce the appearance of small pali. Diameter seven lines ; 

 height three lines. 



Found by M. Walton in the Inferior Oolite at Charlcomb and English Batch. 



This species, together with M. dej)ressa} and, in all probabiUty, M. numismalis^ con- 

 stitute in the genus Monilivaltia a small section, characterised by the discoidal form of the 

 coralhim, and the completely horizontal position of the wall. At first sight they may easily 

 be considered as referable to another family, and placed in the genus Cydolites; but, on a 

 closer examination, it will be found that they are not provided with synapticulge, as is 

 the case with all Fungidse, and do not differ in structure from true Asfreidce. This 

 discoidal form alone distinguishes these fossils from the other species of Montlivaltia ; but 

 that peculiarity does not appear to us of sufficient value to authorise the establishment of a 

 separate genus. 



8. Montlivaltia depressa. Tab. XXIX, figs. 5, 5a. 



Corallum discoid, much resembling a Cydolite by its general form ; its under surface 

 slightly concave, and covered with a thick epitheca; its upper surface convex, fossula 

 circular, and very superficial. Sei^ta straight, thin, unequal, and forming four cycla; 

 those of the first cyclum extending almost to the centre of the calice. Diameter one inch ; 

 height three lines. 



Pound at Wotton-under-Edge, by M, Walton. 



We have seen but one very ill-preserved specimen of this fossil, and have not been able 

 to ascertain all its characters in a satisfactory manner. It appears, however, to belong to 

 the section of the discoidal MontUccdtia, and may easily be distinguished from the two 

 other species of the same lenticular form by the disposition of its septa, which are much 

 less numerous than in M. numismalis^ and much thinner and less strongly denticulated 

 than in M. lens.'*' 



^ Tab. xxix, fig. 5. 



2 Tliecopfiyllia mimismalis, D'Orbigny, Prod, de Palcont., vol. i, p. 321. 



3 ThecopJiyllia numismalis, D'Orbigny, Prod., vol. i, p. 321. 

 '» Tab. xxvi, fig. 7. 



