134. BRITISH FOSSIL CORALS. 
thick epitheca, presenting concentric folds or wrinkles, and a very small central cicatrix. 
Calice circular, and somewhat convex; fossula shallow and oblong.  Septa straight, 
exsert externally, unequally developed, termimated by a strongly denticulated edge, and 
forming five complete cycla, four of which are well developed ; those of the second cyclum 
differ but little 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 sey/a 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 JZ. depressa,' and, in all probability, IZ. xumismalis,’ con- 
stitute in the genus A/ontlivaltia a small section, characterised by the discoidal form of the 
corallum, 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 Cyclolites; but, on a 
closer examination, it will be found that they are not provided with synapticule, as is 
the case with all Fungidé, and do not differ in structure from true Astreide. This 
discoidal form alone distinguishes these fossils from the other species of Wondlivaltia ; but 
that peculiarity does not appear to us of sufficient value to authorise the establishment of a 
separate genus. 
8. MontnivaLtia DepREssa. ‘Tab. XXIX, figs. 5, 5a. 
Corallum discoid, much resembling a Cyclolite by its general form ; its under surface 
slightly concave, and covered with a thick epitheca; its upper surface convex, fossula 
circular, and very superficial. Seta 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. 
Found 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 Montlivaltia, and may easily be distinguished from the two 
other species of the same lenticular form by the disposition of its seyta, which are much 
less numerous than in J/. xwmismadlis,? and much thinner and less strongly denticulated 
than in JZ. lens.* . 
1 Tab. xxix, fig. 5. 
Thecophyllia numismalis, D'Orbigny, Prod. de Paléont., vol. i, p. 321. 
8 Thecophyllia numismalis, D’Orbigny, Prod., vol. i, p. 321. 
Tab. xxvi, fig. 7. 
