Mr. J. W. Salter on some new Palaozoic Star-fishes. 331 



under surface (4, c) the marginal plates are highly convex, and 

 between them lies a double row of central plates of an hour-glass 

 shape, on the outer sides of which, and between them and the 

 marginal row, is a large round aperture on either side — the 

 passage for the suckers or feet. The marginal plates bear a row 

 of spines as long as the width of the arm, and striated across. 



The oral pentagon is made up of twenty bones, five pairs of 

 which are the central row enlarged (*), and these diverge at a wide 

 angle, and nearly join the neighbouring pairs ; the other five 

 belong to the lateral rows, and are linear (^), set parallel, and 

 bear the conspicuous, triturating combs of spines. The oral 

 ossicles in this species form an angular pentagon, being made 

 up of straight pieces ; in some others they are arched, and give 

 an ogive form. 



Loc. Abundant and of all sizes in the quarry at Leintwar- 

 dine. The environs of Ludlow have been rendered classic by 

 the great author of ' Comus.^ 



2. P. leptosoma, n. sp. PI. IX. fig. 5. 



P. disco tenuissimo, brachiis angustis, superne ossiculis alternatis 

 semisulcatis ; infra ambulacro angustissimo impresso, spinis bre- 

 vibus, paucis ? ; ore rosaceo. 



This is also a very abundant species, and occurs in hundreds 

 over the surface of the slabs, just as Ophiura are now found in 

 clusters upon the muddy bottom, the dredge often coming up 

 filled with a single species. 



It is a small star-fish, the rays seldom above an inch long ; 

 and the central disk apparently very thin, and often scarcely 

 visible on the stone. The oral pentagon, however, is always 

 conspicuous, and is of a beautiful petaloid shape, made up of a 

 series of ogives, the salient angles of which are inserted into the 

 base of the arms, and formed of three pairs of bones (while in 

 P. Miltoni only two are distinct, and these are set in an angular 

 form) ; small spines are afiixed to their extremities. 



The arms appear more slender than they really are, in conse- 

 quence of their being only convex along the median line ; the 

 sides of the ossicula are very thin, and only by careful search 

 can the prominent margins be seen. These are thickened a little 

 along the outer and the hinder edges, but not in front ; and the 

 squarish plates (more transverse near the mouth and elongate 

 towards the tips) are rounded-off behind and pointed in front, so 

 as to be somewhat falcate. 



The plates of the lower surface are four, as in the other spe- 

 cies, the lateral ones squarish, and bearing rows of short spines ; 

 the middle rows are exceedingly narrow, and ofi'er an excellent 



