THEONOA. 181 



Diagnosis. Zoarium composed of many erect, irregular sheets. 

 The sheets are tall, irregularly siuuous, and branched, having 

 loose, funnel-shaped cavities between them. The zoarium is 

 roughly hemispherical in form. 



The radial ridges are long and fairly continuous. The summits 

 are flat, and contain generally three or four apertures in width ; 

 but in places they expand, and contain six or seven in width. 

 The ridges occur on both sides of the sheets. 



DISTRIBUTION. 



ENGLAND : 



Inferior Oolite : Postlip, near Cheltenham ; Cleeve Hill. 

 FOREIGN : 



Bajooian: Montvaux and Vittonville, near Metz (fide Friren). 



Affinities. This species is very well marked by its erect, thick 

 fronds or sheets. It was well figured by Haime, and the British 

 Museum contains some fine specimens belonging to the Brodie 

 Collection. 



LIST OF SPECIMENS. 



D. 2117. Inferior Oolite. Cleeve. Brodie Coll. 

 D. 2197. Young form. Inferior Oolite. Cleeve. Brodie Coll. 

 D. 2128, D. 2134, D. 2187. Near Leckhampton. Brodie Coll. 

 D. 2129. Inferior Oolite. England. Brodie Coll. 



3. Theonoa distorta (Lamouroux), 1821. 



SYNONYMY : 

 Tilesia distorta, Lamouroux, 1821, Expos. Meth. p. 42, pi. Ixxiv. fig. 6 (non 



fig. 5). 



Bronn, 1825, Pflanzenth. pp. 21, 42, pi. vi. fig. 5. 



,, ,, Defrance, 1829, Diet. Sci. nat. t. liv. p. 365. 



,, Blainville, 1830, ibid. t. Ix. p. 380, pi. xli. fig. 5. 



,, Blainville, 1834, Man. Act. p. 415, pi. Ixiii. fig. 5. 



,, M. Edwards, 1836, in Lamarck, Hist. Nat. Anim. s. Vert. 



ed. 2. t. ii. p. 316. 



n Michelin, 1846, Icon. Zooph. p. 232, pi. Iv. fig. 7. 



,, ,, ex. syn. Bronn, 1848, Nomencl. p. 1264. 



,, ,, Bronn, 1849, Enum. p. 143. 



,, ,, D'Orbigny, 1849, Prod. Pal. t. i. p. 316. 



