ACTINOPORA. 



175 



2. Actinopora diplopora (Branco), 1879. 



SYNONYMY : 



Defrancia diplopora, Branco, 1879, Unt. Dogger Deut. Loth.: Abh. geol. 

 Specialk. Elsass-Loth. Bd. ii. Ht. 1, p. 131, pi. vi. 

 fig. 9. 

 Actinopora ,, Friren, 1893, Bry. ool. inf. Metz : Bull. Soc. Hist. nat. 



Metz, ser. 2, t. vi. p. 57. 



,, Gregory, 1896, Eev. pt. vi. : Ann. Mag. Nat. Hist. ser. 6, 



vol. xvii. p. 289. 



Diagnosis. Zoarium large and thin, and several often grow 

 together into a semi-confluent encrustation. The ridges are from 

 35 to 50 in number. They are very thin, irregular, and high, 

 and extend to the margin of the zoarium. They sometimes 

 branch. "No peripheral selvage. In some zoaria var. alta the 

 ridges are very high, and the central depression accordingly very 

 deep. 



DISTRIBUTION. 



ENGLAND : 



Great Oolite : near Bath. 



Inferior Oolite : near Stroud, and near Leckhampton. 

 FOREIGN : 



Zone of Sonninia sowerbyi : Ars and Montvaux, near Metz. 



Description of Figure. PL IX. Fig. 6. Part of a zoarium, 

 X 12 dia., and the whole zoarium natural size. Great Oolite: 

 near Bath? B. 2295. 



Affinities. This species is most closely allied to A. pJiillipsi 

 (Haime), of which I at first regarded it as a large variety. It 

 differs from this, however, by three characters: (1) it has no 

 flat margin, as the ridges reach to the edge of the zoarium ; 

 (2) the ridges are thinner, more distant, and nearly twice as 

 numerous; (3) the ridges are irregular, being sinuous, and often 

 not continuous. These characters appear sufficient to demonstrate 

 the distinctness of this species. 



This may be the Defrancia ranvilliana, D'Orb., 1 but D'Orbigny's 

 diagnosis is so short that his species is quite indeterminable. 



1 D'Orbigny. Prod. Pal. t. i. (1849) p. 317. 



