VII. 194 F. A. Bather — Studies in Edrioasteroidea. 



(London, 1900). Some of the points will be better understood 

 after publication of Study III, which will deal with E. Bigsbyi. 



The terms used and the arrangement followed in the present 

 account are the same as those in Study I. Dinocystis Barroisi. 1 



Horizon and Locality. 



The specimens preserved under this name in the Museum of 

 Practical Geology, V - 7 - 7 -, were obtained during the summer of 184:7 

 from the Caradoc beds, two miles west of Ysputty Evan ; that is to 

 say, about two miles south of Pentre Voelas, and therefore in 

 Denbighshire and not in Caernarvonshire as stated by J. W. Salter 

 (op. cit,, 1866, p. 262) and by K. Etheridge, sen. (op. cit., 1881, 

 pp. 395 and 407). Mr. Etheridge informs me that the specimens 

 were not found in situ, but were collected by Mr. Gibbs from a wall 

 of loose stones, all of the same material. There seems, however, 

 no reason to doubt that they came from the Caradoc beds of some 

 quarry in the immediate vicinity, for they have the well-known 

 characters of those beds. The matrix is an indurated sandstone, 

 hardly to be described as " schistose " in any modern sense of the 

 word. It contains remains of crinoid stems, brachiopods, and 

 corals ; the calcareous portions of these have been dissolved from 

 the outer portions of the stone, and the same is the case with the 

 edrioasteroid. 



Description of the Type-Specimen. 



This consists of an internal cast of the whole individual (PI. VIII) 

 and an external impression of its abactinal surface (PL IX). There 

 is also preserved, in the central region of the abactinal surface of 

 the cast (PL VIII, Fig. 3), a small portion of the original theca. 

 Except when said to be otherwise, the statements refer to the 

 internal cast. 



The periphery is subpentagonal ; the sides of the pentagon 

 correspond to the interradial areas, and are slightly convex. The 

 length along the sagittal plane is 36 mm. The transverse diameter 

 is 32 mm. 2 The greatest width of each side is about 20 mm. 



From the periphery, the theca rises rather steeply, then curves 

 gently over to a slight depression around the actinal pole ; towards 

 the under surface it bends more suddenly. Seen from the side 

 (PL VIII, Fig. 2) the theca looks like a round cap squashed in at 

 the top. If the fossil be placed on a flat surface, it reaches a height 

 of 18 5 mm. ; but the actinal pole is about 3-5 mm. below this. 

 The under surface is excavate to about 5 mm., so that the length of 

 the polar axis is about 10 mm. The specimen does not appear 

 to have undergone more compression along this axis than it was 

 capable of effecting spontaneously during life. 



1 Geol. Mag., n.s., Dec. IV, Vol. V, pp. 543-548, pi. xxi ; Dec, 1898. 



2 To dispel possible perplexity, it may be said at once that Forbes' measurements 

 are very inaccurate, sometimes inexplicably so. 



