﻿8 FOSSIL ASTEROIDEA. 



previously borne upon the plates, which appear to have been rather large and 

 uniform. 



Very few, if any, pedicallariee appear to have been borne on the actinal inter- 

 mediate plates. 



The character of the mouth-plates and their armature cannot be made out in 

 any of the examples I have examined. 



The supero-marginal plates are only exposed in the marginal view of the 

 example under description. Their height is seen to be less than that of the 

 infero-marginal plates, and they are also rather smaller both in length and breadth ; 

 about twenty-two appear to be present between the median interradial line and the 

 extremity of the ray. In their general character and ornamentation they resemble 

 closely those of the infero-marginal series. 



From another example, also contained in the British-Museum Collection, and 

 bearing the registration mark " E. 2037," in which the abactinal surface is shown, 

 the following details are supplemented. 



The abactinal area is covered with small, regular, hexagonal plates or paxillar 

 tabula, which are slightly rounded superficially, and a little bevelled on the 

 margin of the tabulum. The surface of the tabulum is covered with punctations 

 or marks left by the granules originally borne on the plate, and here and there 

 small pedicellarian foramina may be seen, usually near the margin of the plate. 

 The plates (or paxillse) of the median radial series are broader than any of the 

 others, the largest measuring about 2 mm. in breadth, and a little more than 1 

 mm. in length. The other tabula are true hexagons, measuring about 1 mm. in 

 diameter or a trifle more, and they are arranged in longitudinal series parallel to 

 the median radial series. Eight or nine series are present on each side of the 

 median radial series on the disk. Opposite the eighth supero-marginal plate, 

 counting from the median interradial line, only the median radial series and one 

 lateral series of tabula on each side of it are present. The median radial series 

 then extends alone and is present at the fourteenth plate, where the ray is broken 

 in the example under description — and looks like continuing further — pro- 

 bably reaching to the extremity of the ray. 



Dimensions. — In the type specimen (figured on PI. I) the major radius is 

 98 mm., the minor radius 48 mm., the thickness of the margin from 9 to 10 mm. 

 The breadth of a ray between the fifth and sixth infero-marginal plates measures 

 about 28 mm. 



Locality and Stratigraphical Position. — The specimen figured on PI. I is from 

 the Lower or Grey Chalk at Burham, in Kent. The species has also been ob- 

 tained from the Upper Chalk at Brighton (Coll. Brit. Mus.) ; and it is sometimes 



