PEOM THE GREAT OOLITE. 18S 



Genus Adelastr^a, Reuss. 



An objection was some time since raised by Eeuss to the use of 

 the unclassical name Confusastrcea^ and attention having been called 

 to this by Prof. Duncan, it must now be abandoned. Adelastrcea, 

 the name applied by Reuss to a species from the Cretaceous beds of 

 Gosau, will now take its place, and Confusastrcea consohri7ia, Con- 

 fusastrcea tenuistriata, and Confusastrcea magnifica, which I have 

 introduced into our coral-fauna, must now be called Adelastrcea con- 

 sobrina^ Adelastrcea tenuistriata, and Adelastrcea magnijlca. Three 

 other species which occur in the Great OoHte of the Boulonnais, one 

 of which has been lately described by me under the name of Gonfus- 

 astrcea Bigauxi, are now also to be referred to the genus Adelastrcea. 



Some very large specimens of a coral appertaining to the genus 

 occur in the Great-Oolite quarry near Great Milton, and some of 

 less dimensions have been taken from the Caps-Lodge quarry ; but 

 whether they are distinct from Adelastrcea magnifica, to which they 

 bear considerable resemblance, I have not yet been able to deter- 

 mine. 



Genus Platastr^a, n. g. 



Clausccstrcea, Milne-Edw. and Haime, in part. 



The genus Clausastrcea is one of those in which there is ample scope 

 for diversity of opinion, for it has been placed among the Astreidce, 

 among the now discarded Tabidata, and in the newly proposed half- 

 way group designated Plesiofungidce. It is now, however, evident 

 that two very distinct forms have been confounded under the name of 

 Clausastrcea. In specimens of Clausastrcea duhia and Clausastrcea 

 Edwardsi, with which I have been favoured by M. de Promentel, 

 there are, as mentioned by him in the description of the species *, 

 very distinct and numerous tabulae, arranged one above the other 

 with great regularity, and extending on the same level across the 

 corallum. They have been observed and figured in another species 

 by M. Etallon, in which the ' same distribution and form are 

 obvious f. 



The other form is represented by two English species, one of 

 which, from the Great Oolite of Combe Down, Bath, has been de- 

 scribed by MM. Milne-Edwards and Haime under the name of 

 Clausastrcea Pratti. The endotheca of this species they describe in 

 the following words : — " The loculi are closed by well-formed and 

 rather numerous dissepiments." In the figure which accompanies 

 the description these are shown %. In weathered specimens from 

 Combe Down, now before me, the nature of these dissepiments is 

 very apparent. They are obviously quite unlike tabulae. 



Under the impression that the so-called Clausastrcea Pratti has 

 an essential columella, the original describers transferred it to the 

 genus Plerastrcea, in which genus it appears in their general work 

 on corals. But from the examination of a number of specimens 



* Introd. Etude Pol. foss. p. 281. t Leth. Bvuntr. pi. Ivii. fig. 5. 



I Brit. Foss. Cor. pt. ii. pi. xxii. fig. 5. 



