MADREPORARIA OF THE BOULONNAIS. 701 
On the several beds of the foregoing section M. Rigaux has 
favoured me with the following additional and important remarks :— 
Bed No. 1, Wimereux. “Two Isastrew very much worn (one 
yery scarce), only found in a pudding-stone of 6 feet thick, at the top.” 
Bed No. 3, Chatillon. ‘The same two Isastrew very much 
worn, found in pudding-stone from 2 to 6 feet thick. It seems as 
if the Isastrec lived in another sea, and were brought twice ‘by 
special currents.” 
Bed No. 4, Belledale. ‘‘Corals are only found in a bed 6 feet 
thick, made up principally of worn-out corals and full of Cidaris 
florigemma. It is the highest real coral-bed in the Oolites, being 
found about the middle of the Virgula-beds.” 
Bed No. 5, Questrecques. ‘‘Corals occasional in a sandy oolite 
bed 3 feet thick.” 
Bed No. 7, Hourecq, Hesdin Abbé. ‘I look upon this bed as 
the representative of the English Coral Rag. It is entirely made 
up of corals and Cidaris florigemma.” 
Bed No. 9, Mont des Boneards. ‘Corals and Cidaris florigemma 
compose the lowest beds.” 
Bed No. 11, Houllefort. “‘ A part of this bed is full of corals and 
Cidaris florigemma.” 
Bed No. 18, Le Wast. ‘The species of corals are numerous but 
the specimens very scarce, if we except the Anabacia, Genabacia, 
and Isastrea moneta.”’ 
Bed No. 14, Hydrequent, Réty, Bléquenéque. ‘‘ Corals confined 
to the lower half, and common in the beds which correspond to the 
planking of Minchinhampton.” 
M. Rigaux further observes that he regards beds 6 to 9 inclusive 
as Corallian, and 10 and 11 as constituting the Lower Grit. 
On looking over the foregoing it will be seen that one species of 
coral occurs in what must be regarded as the equivalent of the 
Lower Portland or Upper Kimmeridge deposits of this country. 
This is obviously affined to the very common and widely distributed 
Coral-Rag species Thamnastrea concinna; and when we observe 
that an unquestionable Portland species, Jsastrwa portlandica, has 
been found by M. Rigaux in the beds of the Middle Kimmeridge, 
we shall find no difficulty in deciding that the coral faunas of the 
Corallian and Portland Oolites graduate into each other. 
Species from the Great Oolite. 
Genus Discoc@nta, n. g. 
(Fam. Astreide ; Subfam. Husmiline.) 
Two specimens of a coral from the Cornbrash of Le Wast, near 
Boulogne, have been received from M. Rigaux, the characters of 
which do not agree with those of any genus with which I am 
acquainted, and I therefore describe the form under the above name 
as follows :— 
The corallum is discoidal, very thin, but becoming thicker by 
