120 DIASTOPORA. 



DIAGNOSIS : 



Zoarium loose and open, the fronds being generally broad, thin, 

 and only slightly contorted. Bilaminate. 



Zocecia visible throughout, the zooecia being long, and the aper- 

 tures distant from one another and irregular in arrangement. 

 The zooacia are regularly cylindrical. The peristomes well raised, 

 giving a rough aspect to the zoarium. 



Formula. p, c, I, r = 2, 0, 3, fr. iQ. 



DISTRIBUTION. 

 BRITISH : 



Cornbrash : Thornboro', Bucks. 



Great Oolite : Bath ; Bredon ; Minchinhampton. 



Inferior Oolite : Stroud (fide Witchell). 



FOREIGN : 



Bathonian : Marquise and Wast, near Boulogne ; Caen, Langrune, 



Lebisey, St. Aubin, in Calvados. 



Bajocian Calcaire ferrugineuse : Saint Quentin, near Metz. 

 Zone of Sonninia sowerbyi : Gingen, "Wiirtemberg. 



Description of Figure. PI. VI. Fig. 4. Part of zoarium with 

 gonoecium, X 15 dia. Inferior Oolite. Loc. ? Holl Coll. D. 5. 



Affinities. There is the usual confusion as to the form to which 

 this name belongs, and therefore as to the type of Diastopora. 

 Lamouroux, as Milne Edwards pointed out, clearly included two 

 species in his D. foliacea. The latter author, however, regarded 

 one of these as encrusting, and for this he retained the name ; 

 but his text, footnotes, and explanation of the plate do not 

 agree. Milne Edwards figured as D. foliacea the form shown in 

 Lamouroux's figures No. 1 and 2 ; and in this sense the name has 

 been accepted. 



I include in this species D. eudesiana, M. Edw., which was 

 described as differing from D. foliacea by its greater flatness. This 

 appears, however, to be due to the lowering of the peristomal 

 portion of the zocecia by wear. A frond from Ranville (Brit. Mus. 

 iS'o. 60239) is of the D. eudesiana type in one portion, and else- 

 where is a typical foliacea. The species D. mettensis, Haime, 

 appears to be founded on eroded fragments, which show promi- 

 nently the sutures between the zooecia. 



