178 THEONOA. 



Diagnosis. Zoarium formed of several confluent discs. Eadial 

 ridges broad and compact ; broken up into short groups or bands. 

 The bands have from 2-4 zooecia in breadth. 



DISTRIBUTION. 



ENGLAND : 



Inferior Oolite : Birdlip Hill and Leckhampton. 

 FOREIGN : 



Bajocian: Plappeville, near Metz (fide Friren) ; Moselle (fide 

 Terquem) . 



Description of Figure. PL X. Fig. 1. Part of a zoarium 

 encrusting Terebratula globata, J. de C. Sow., X 12 dia. Inferior 

 Oolite: Birdlip. 67613. 



Affinities. This is the type and only known species of the 

 genus. Its nearest ally is Actinopora diplopora (Brauns), in which 

 a tendency to the breaking up of the radial ridges can be seen. 

 In K. terquemi (Haime), however, this is carried to an extreme ; 

 the ridges are broader, closer, and flatter, and less numerous. 



LIST OF SPECIMENS. 



67613. On Terebratula globata, J. de C. Sow., var. birdlipensis, "Walk. 



Inferior Oolite. Birdlip. 

 D. 2189. On Terebratula globata, J. de C. Sow. Inferior Oolite. Near 



Leckhampton. Brodie Coll. 

 D. 1802. On Terebratula perovalis, J. de C. Sow. Inferior Oolite. 



THEONOA, Lamouroux, 1821. 

 SYNONYM : Tilesia, pars, Lamouroux. 



Diagnosis. TheonoidaB in which the zoarium is massive, and 

 consists either of dense, rounded masses, thick encrustations, or 

 erect, thick fronds. The surface is crossed by broad, well-marked 

 ridges. The ridges may expand in some species into broad, tabular 

 elevations. 



Type species. T. clathrata, Lamouroux, 1821. 



Affinities. Lamouroux, in 1821, founded the two genera Tilesia 

 and Theonoa. Haime, in 1854, merged these, retaining for the 

 genus the name Theonoa, though this was the later in description. 

 As the two genera were published simultaneously, it would be 



