16 



PUOF. P. MATITIN DUT^CAT^'S EETISTOT^ OE TTTE 



III. Alliance PLACOTROCHOIDA. 



Simple Turbinolidse, free or attached, compressed, with an essential, 

 more or less lamellar or elongate columella, rarely with pali. 



Genus Placotrochus, Ed. & H. 

 Genus Sphenotrochus, Ed. & H. 

 Genus Nototrochus, Duncan. 

 Genus Placocyathus, Ed. & H. 

 Genus Platytrochus, Ed. & H. 



Genus Placoteochus, 3IM. Milne-Edwai^ds Sf Jules Haime, 

 Ann. des Sci. Nat. 3*^ ser. t. ix. p. 282 (1848), amended. 



The corallum is simple, straight, cuneiform, flabelliform, and 

 compressed or cornute, or more or less cylindrical and compressed. 

 The columella is essential and is lamellar, horizontal, sharp, and 

 entire at the surface, or crenulated. Septa exsert or not. Costse 

 developed, and often in crests or spinulose. 



Localities. — Recent. Chinese seas, Philippines, N. Australia. — ■ 

 Fossil. Miocene of West Indies, Australia, Europe. 



This is a well-marked genus, and some of tlie species are mucli 

 compressed and extended laterally ; others are deltoid and com- 

 pressed ; and one Sicilian form is, cornute, with an epitheca. 

 The lamellar and essential columella is very characteristic. 



G-enus Sphettoteochus, MM. Milne-Edwards Sf Jules Haime, 

 Hist. Nat. des Corall. vol. ii. p. 65. 



The corallum is free, straight, cuneiform, compressed. Septa 

 exsert or not ; the principal reach the essential lamellar columella, 

 which is lobed or knobbed at the free surface on the floor of the 

 elliptical calice. Base bluntly j^ointed, truncate, or emarginate. 

 Costse projecting straight or more or less in zig-zag. Lateral 

 costse crested or not. 



Localities. — Recent. Mediterranean and N. Africa ; coast of 

 Brazil ; European coasts of N. Atlantic ; S. Australian coasts. — 

 Fossil. Cretaceous : Germany. Eocene of Erance, Belgium, and 

 Alabama. Miocene of Erance and Germany. Pliocene of 

 England. Cainozoic : Australia and New Zealand. 



The species described by M. de Eromentel from the Cretaceous 

 of Erance would appear to be more like a Flacotrochus than a 

 Sphenotrochus . 



There is a common little simple coral in the Tertiaries of Aus- 

 tralia which has given the Eev. T. Woods and myself much 



