186 R. F. TOMES ON THE GREAT-OOLITE MADREPORARIA. 



This species possesses characters between Isastraza limitata and 

 Isastcea explanulata. It also occurs and is common in the Fairford 

 coral-bed. 



Isastr2Ea explaktjlata, M.-Edw. and Haime, Brit. Foss. Corr. p. 115, 

 tab. xxiv. fig. 3. 



Astrcea explanulata, M'Coy, Ann. Nat. Hist. ser. 2, vol. ii. p. 400 

 (1848). 



As is the case with Isastram limitata, the present coral occurs both 

 as a massive and a dendroid form. But the branching variety may 

 be regarded as the ultimate, and therefore the most typical growth. 

 The calices on the branches are even more superficial than those of 

 the massive variety, and often have no depression whatever, but 

 present the appearance of hexgonal patches of crowded septa, raised 

 just their own thickness from the surface of the corallum. Their 

 outward ends pass in between the outer ends of those of the con- 

 tiguous calices. This interlapping of the septa is what I have not 

 seen in any other of the Astraeidee ; and it led me at one time to place 

 this species in another genus. But as it is little observable on the 

 more massive parts of the corallum, but is mostly confined to the 

 newer growth, of course it is not a valuable character. 



This coral occurs and is common at Fairford and at Burford ; and 

 I have received, by the kindness of M. Bigaux, a specimen from the 

 Great Oolite near Boulogne. 



Genus Latimjeandra, d'Orb. 



It is probable that the Latimceandrm of the Secondary formations 

 need a much more searching investigation during the earlier periods 

 of their growth than they have as yet been subjected to, and to 

 have their relationship with Chorisastraea, Heterogyra, and Phyllo- 

 gyra more clearly made out. 



Lattm.eaxdea lotharixoa, E. de From. Cat. Polyp, de l'Tonne, 1856 ; 

 Tomes, Proc. Geol. Assoc, vol. vi. p. 160. 



Meandrina lotliaringa, Mich. Icon. Zooph. p. 100, pi. xxii. fig. 2. 



Since the appearance of my paper in the sixth volume of the 

 ' Proceedings ' of the Geologists ' Association, I have met with this 

 species in the Great Oolite near Burford, and have examined speci- 

 mens from Fairford in Mr. Slatter's collection. From the locality 

 before mentioned by me (the railway-cutting near Bollright, 

 Oxfordshire) I have also obtained a further supply of specimens, 

 and have taken a single example from the surface of a field contiguous 

 to the Stonesfield railway-cutting. 



Genus Chorisastr^a, E: de From. 

 Chorisastejea obtusa, d'Orb. sp. 



Amblopliyllia obtusa, d'Orb. Prodr. Paleont. t. i. p. 285(1850). 



Thecosmilia ? obtusa, M.-Edw. and Haime, Pol. Foss. terr. Pal. 

 p. 78 (1851). 



