150 EOCENE AND LOWER OLIGOOENE CORAL FAUNAS. 



Genus PLATYCCENIA gen. nov. 



Colony flat, iiicnisting ; corallites rather small, usually circular, joined 

 directly by their solid walls or by an echinulate coenenchyma, across which 

 costpe may sometimes be traced by the arrangement of the echiuulations. 

 Calicular margins very slightly or not all elevated. The outer surface of 

 the free portion of a corallite marked by minute, crowded, acute costse; in 

 some instances a costa is simply a row of small spines. Frequently there 

 are costse between the septa as Avell as corresponding to them. The septa 

 are few in number, are solid, formed of trabeculse directed horizontally 

 inward. The septal margins dentate. The smallest septa are represented 

 by rows of spines placed one above another. Very few granulations on 

 the septal faces. Calicular fossse, rather deep ; colmnella a rather tall 

 pointed style. Endotheca present. Reproduction by budding between the 

 corallites or directly from the base of the peripheral corallites. 



This genus belongs, systematically, near Astrocoenia.^ It is distin- 

 guished from Astrocoenia by the coraHites usually not being directly united 

 by their walls. 



A few remarks should be made on the relationship existing between 

 this genus and Astroccenia pulcheUa M.-Edw. and H.^ ]\Ir. R. F. Tomes^ has 

 pointed out that this is probably not an Astrocoenia. The corallites are not 

 directly united by their walls. As this character is one by which Platy- 

 coenia is separated from Astroctx'nia, it might be thought Astrocoenia 

 pulcheUa belongs to the genus here proposed. The septa of tliat s})ecies 

 are described as having "their upper edge entire and convex." This char- 

 acter removes Astrocxenia ])ulcJieUa from both Astrocoenia and Platycoenia. 

 It almost certainly belongs to a new genus. 



Platyc(Knia .tacksonensis sp. nov. 

 PL XVII, figs. 9 to 9c. 



Colony small, 21 nun. in diameter, flat, incrusting. Calices deep, 1.5 

 to 2 mm. in diameter, circular or irregular in outline ; united directly by their 

 solid walls or separated by a little echinulate coenenchyma. Calices Avhich 



'Cf. Felix, Beitrage zur Kenntniss (Ut Astrocceninic : Zeitsch. Deiitsch. geol. Gesell., A'ol. L, 

 Pt. II, 1K98, pp. 247 ct seq. 



'Mou. Brit. Foss. Corals, Pala'iitogr. Soc, p. 33, pi. v, figs. 3, 3a-3c. 

 3Qiiart. Jour. Geol. Soc. Loudon, Vol. XLIX, Nov., 1893, pp. 569, 570. 



