274 



XVI. The FIG PENTACRINITE, of Gloucestershire, described in 

 the Philosophical Transactions ; see Letter XXV. 



XVII. The PENTACRINITE, of Yorkshire. 



To these I shall add the following fossils, which have been 

 described by other authors, but whose rarity has hitherto 

 prevented their nature from being duly investigated. 

 XVIII. The Encrinites with four rays. This fossil is spoken of by 

 Mons. Guettard, in the Memoirs of the Royal Academy of 

 Sciences, for the year 1755*. He remarks, that in this spe- 

 cies of encrinite each of the principal rays is divided into 

 two, which are again divided into two others, from which 

 proceed a considerable number of small branches. The 

 opinion of Mr. Walch, that this species might, perhaps, be 

 referable to the pentacrinites, derives support from the ex- 

 istence of quadrilateral asteriae, which would, of course, 

 have belonged to a pentacrinite possessing four arms. 

 XIX. The Encrinite with five or six rays. Such a fossil is described 

 by M. Harenberg, in his treatise De Lilio Lapideo ; but it 

 does not appear to have been seen by any other author. 

 XX. The Encrinite with eight rays and a square base. This spe- 

 cies is mentioned by M. Schulz, in his description of the 

 petrified stellce marina. No other author appears to have 

 described this fossil. 



XXI. The Encrinite with twelve rays and a hexagonal base. This 

 encrinite is figured and described by Rosinus, in Plate I. and 

 page 34 of his excellent treatise de Lithozois. Rosinus de- 

 scribes the trochitae of this species as being characterized 

 by concave articulating surfaces, bearing the figure of a 

 pentapetalous flower, with a similar but much smaller 

 floweret in the centre. 



* Recueilde Monumens des Catastrophes, &c. Tom. II. Sect, II, p. 89. 



