110 MADREPORARIA. 



gather, there is no record of this species at all. It does not exist. Defrance's original 

 specimen he called Astrcea incrustans. But I have failed to find any description of this 

 original. Let us then overlook all that and start again with Milne-Edwards' species Porites 

 incrustans, the original of which we may now regard as this specimen from the Mouth of 

 the Rhone. We should again have something definite except for the indefiniteness of the 

 " species " founded upon it. It has loomed too large as a species. So important was this 

 " species " that it was stated by Milne-Edwards and Haime to include that established by 

 Michelin and called P. collegniana. Not only was there no evidence for this, but Michelin's 

 coral was a Goniopora with more than twelve septa. 



Again, as usual, such a species has been made to include fossil specimens from all 

 parts. In fact, almost every encrusting Porites has been placed automatically into the species 

 P. incrustans. For instance, in 1864, Martin Duncan* claimed to have recognised this " species " 

 at Kurrachee (see Vol. V. p. 232), and used the discovery as part of the cumulative evidence 

 that the stratum was Miocene. What is especially unfortunate is that such " identifications " 

 render descriptions and figures unnecessary. Reuss, for instance, recorded in 1871 fossil 

 Porites from fourteen localities in the extensive Miocene beds of Austro-Hungary. The 

 greater number were simply called P. incrustans Defr. Only one of them did he illustrate, 

 and his figure shows the specimen to have been a Goniopora.^ 



When all these imaginary relationships are swept away, we have the simple facts above 

 detailed left ; even then there is the danger that the original description was not that of a single 

 specimen, but was built up of characters supplied by several, with perhaps one or two details 

 borrowed from Michelin's description and figure. If so, this coral must be re-discovered 

 and re-described. 



100. Porites Alessandria 1. (P. Alessandrina prima.) 



[Stazzano, near Novi- Alessandria (Upper Miocene, " Tortonian "), coll. Michelotti ; 



Geological Museum, Rome.] 



Description. — The corallum forms smooth, thick stems (2 cm. thick), cylindrical or slightly 

 compressed. 



The calicles are quite superficial, 1 • 5 mm. in diameter. The walls, built of thin, 

 horizontal flakes, not very porous, but with bends and slight folds. The twelve septa often 

 seem as if they were embossed upon the surface of the flakes ; except for slight angular points, 

 they are smooth and show clear traces of the typical septal formula in which the fusion is 

 complete. The points of fusion sometimes end free, sometimes abut against a ring. They do 

 not swell into pali, and the columellar tubercle is conspicuous. 



This is a true Porites and differs from all others so far recorded. The fact that the 

 skeletal elements are formed mainly of flat flakes parallel with the surface, is a familiar 

 adaptation in recent forms (Tables IV., Vols. V. and VI.). The presence of the typical septal 

 formula establishes beyond doubt the true position of this form. 



• Ann. and Mag. Nat. Hist. xiii. (1864) p. 305. f See Vol. IV. p. 124. 



