428 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 6, 



turbinate shape does not depend upon the incomplete development 

 of the individual, the necessity for a new genus is evident ; but in 

 the other characters this Pater ocyathus Guadalupensis is closely allied 

 to the genus Brachycyathus. There is no reason for separating the 

 San Domingo forms from the genus Brachycyathus, but they con- 

 stitute a group not sufficiently resembling the species B. Orbig- 

 nyanus* to be placed in close alliance with it. 



2. Placocyathus Barretti, spec. nov. PI. XVI. figs. 1 a-1 c. 

 Var. 1. 



A fragment of a simple corallum, with a curved lamellar columella 

 and with the pali destroyed, probably belongs to the same species as 

 the Jamaican form, page 437. 



From Postrero. Brit. Mus. 



Var. 2. 



A variety with more rounded ends, less epitheca, and more distinct 

 costse than seen in the Jamaican form. 



From Postrero. Brit. Mus. 



3. Trochocyathtjs cornucopia, Edwards & Haime (Turbinolia cor- 



nucopia, Michelin). 



A specimen of this species from the San-Domingan shale is in the 

 British Museum, The species is common in the Vienna Basin and 

 at Tortona. 



4. Placotrochus Lonsdalei, spec. nov. PI. XV. figs. 2 a, 2 5. 



Corallum simple, straight, compressed ; surrounded by a delicate 

 but complete epitheca, through which the rounded, badly developed 

 costse can be seen. The epitheca is delicate and pellicular for nearly 

 halfway up the wall, where it presents a slight constriction ; it is 

 most dense above and below this constriction, and presents no other 

 folds. Costse numerous, very indistinct, except the two lateral ones, 

 which have a well-marked crest projecting like the cutwater of a 

 boat, and at first not following the line of the wall, but being car- 

 ried outwards and downwards, forming an angle, and then following 

 the line of the wall. The costse are most prominent at the angle, 

 and the crests diminish in width towards the basilar mark, and just 

 above this there is the appearance as if there had been a small spine. 

 The margins of the crests and the basilar mark form an angle quite 

 equal to a right angle. The basilar mark is distinct, but small, and 

 not eroded, though flat. Calice elliptical. The long axis is termi- 

 nated by the crested costse, and the widest part of the short axis 

 corresponds to a prominent part of the margin on each side. Prom 

 this prominent part the margin gradually slopes to the crested costse. 

 The plane of the long axis is thus lower than the short. The long 

 axis is exactly twice the length of the short one, excluding the 

 salient crests. Width of the calice -i- inch ; length ± inch. Possa 

 large and moderately deep. Columella essential, long, free to but a 

 slight extent, formed of a thin vertical lamina with a rather arched, 



* This species is found in the Neocomian (Hautes Alpes), 



