208 HETEROPOEA. 



gave the same name to a species from the Crag ; the Jurassic form, 

 however, differs from the Crag species by the greater closeness 

 of the zocecia, and greater disparity between the zooacia. 



SPECIMEN. 

 60210. Bathonian Calcaire a polypiers. Ranville. Tesson Coll. 



3. Heteropora laminata, Gregory. 



SYNONYMY : 



Heteropora laminata, Gregory, 1896, Rev. pt. vi. : Ann. Mag. Nat. Jlist. 

 ser. 6, vol. xvii. p. 295. 



Diagnosis. Zoarium encrusting, growing in layers, superposed 

 into thick masses. The surface of the zoarium is level or raised 

 into monticules. Mesopores irregular in distribution; generally 

 numerous. 



Distribution. Bradford Clay : Bradford. Inferior Oolite : 

 Dorset. 



Description of Figures. PI. XI. Fig. 2. Zooecia and mesopores, 

 X 22 dia. Inferior Oolite : Dorset. B. 2300. PL XI. Fig. 3. 

 Part of zoarium, x 18 dia. Inferior Oolite : Dorset. D. 2255. 



Affinities. This species differs from H. conifer a mainly by 

 zoarial characters, though the mesopores are generally more 

 numerous. The fact that the mesopores are useless as specific 

 guides is shown by Pig. 20, of which both parts are drawn from 

 the same specimen. The left-hand figure exhibits abundant 

 mesopores almost surrounding the zocecia ; while in the other 

 figure mesopores are rare, and occur only in the angles between 

 the zooecia. This shows that Haime was correct as to the vari- 

 ability in the number of these structures, though by his refusal 

 to admit any value to their complete absence, he underrated their 

 significance. 



LIST OP SPECIMENS. 



B. 2300. Inferior Oolite. Dorset? Figd. PI. XI. Fig. 2. 



D. 2255. ,, Dorset. Figd. PL XI. Fig. 3. 



D. 1826. Bradford Clay. Bradford. Variety with prominent monticules. 



