MESOZOIC RADIATA. 55 



cone downwards), each having a prominent tubercle in the 

 centre, adhering laterally by only a short portion of its mar- 

 gin ; second costals horseshoe-shaped ; scapula cuneiform_, as 

 long as wide ; from which two arms arise, of eight or nine 

 joints, the last being cuneiform and supporting two hands, the 

 inner of nine and the outer of fourteen or fifteen joints, the 

 last cuneiform and giving off a lateral finger, and after four- 

 teen or fifteen joints more another (total number of fingers 

 unknown, but small). 



In the great number, size, and mode of insertion of the auxi- 

 liary side-arms this agrees with the P. Britannicus (Schlot.), (P. 

 BriareuSy Mill.), but differs in its small size, broad oval penta- 

 petalous markings of the columnar joints, and from that and all 

 allied species it strongly differs in the first costals not being pro- 

 longed into a cone down the sides of the column. 



There are clearly two species confounded by Goldfuss under 

 the name P. scalane , one of which, figured on the 60th plate of 

 his ' Petrefacten,' is much allied to this ; the other figures on 

 pi. 52 of the same work differ considerably, but agree witb nu- 

 merous authentic specimens I have seen of that species from the 

 German oolites, and also with some from our lower oolite at 

 Dundry; the latter is therefore the most proper type of his 

 species. 



Marlstone, Gloucestershire. 



(Col. University of Cambridge.) 



{Astero'ida^.) 

 Goniaster [Goniodiscus) rectilineus (M'Coy). 



Sp. Char. Sides straight or nearly so ; on tbe dorsal surface each 

 side has eight finely granulated, moderately convex marginal 

 ossicles, of which the two end or " ocular '' plates are tri- 

 angular and the four intermediate ones are quadrate, all of 

 one length, the width of each equal to half its length ; the os- 

 sicles of the oral side are similar except the triangular plate 

 at each end, which is there replaced by three smaller ones ; 

 plates of the disc small, polygonal and minutely granulated. 



* Prof. Forbes having recently published in the * Memoirs of the Geol. 

 Survey of Great Britain ' short descriptions of a number of new chalk star- 

 fishes, I trespassed on his good-nature so far as to send the notes and rough 

 sketches of mine for identification. The one above described is distinct from 

 any of his, but he suggests that the straightness of the sides may result from 

 the suppression of one of them : — the specimen I first sketched may have 

 bi^en four-sided, for the two angles preserved are pretty nearly of 90°, but 

 the second specimen has portions of its five sides preserved, and has all the 

 above characters. 



