426 Two hitherto u?id escribed Species of Radidria, 



the marlstone at the point where it is carried up into the cliff, 

 to the north of the great fault, at the Peak Hill, near Robin 

 Hood's Bay (see Phillips's Geology of Yorkshire), near the 

 lower part of the stratum, where it blends with the lower 

 lias. The figure represents the object reduced to two thirds 

 of the real size. The slab on which the fossil is pre- 

 served is of a rather micaceous nature, a matrix generally 

 unfavourable to preserving minute characters; and a portion 

 of the fossil having adhered to the upper part of the rock, 

 which fell in pieces, the view presented is rather that of the 

 internal than the external structure of the animal. The cen- 

 tral circle, the situation of the mouth, is preserved very dis- 

 tinctly ; and, proceeding with considerable regularity from 

 this, is a series of rays 20 in number. Those rajs near 

 their base bear the sulcus (furrow) which runs under those of 

 recent ^steriae; but towards their apex they become more 

 worn and thin, showing, in several places, a small wiry line, 

 with short ribs branching off at right angles, apparently a 

 species of appendage, resembling what represents the vertebral 

 column and ribs in the turtle, and which is observable in 

 recent ^4steriae. There are also slight traces of transverse 

 grooves on the whole surface of each ray; but these are gene- 

 rally almost obliterated. Along the margins are extremely 

 regular rows of small rhomboidal perforations, or cells, from 

 which proceed a series of lateral filaments, or delicate length- 

 ened papillae ; but on the surface of the fossil, it merely pre- 

 senting to us the interior, no papillae are preserved. The 

 apex of such rays as have not been broken off prior to the 

 animal's being entombed are obtusely pointed. Having met 

 with no species with which this corresponds, I will venture, as 

 one more slight tribute to the high scientific character of 

 R. I. Murchison, Esq., to call it ^sterias Murchison/. nifcib 

 Fig. 64. represents a species of Ophiura [reduced to two 

 thirds of the real size] from the same stratum; but not so low 

 in the series, and found at Staithes, a few miles further to the 

 north. It bears some resemblance to Ophiura Miller/, but 

 differs in two or three particulars. [A figure of O. Miller/, 

 copied from that in Phillips's Geology of Yorkshire, pi. 13. fig. 

 20., is given in our III. 275.] The base of each ray has been pro- 

 tected by two strong heart-shaped plates, the spaces between 

 which would seem to have been rather flexible, but protected 

 by small orbicular scales, or plates, which are, however, rather 

 indistinct. The most evident distinction is in the arrange- 

 ment of the plates of the rays: as in O. Miller/, we have 

 here three rows ; but, instead of the dorsal row being, as in 

 that species, of double the width of the lateral ones, the 



