56 FOSSIL ASTEROIDEA. 



The supero-marginal plates are only two in number, counting from the median 

 interradial line to the extremity, or four from the tip of one ray to the tip of the 

 adjacent ray, exclusive of the odd terminal or " ocular " plate in each case. They 

 form a broad border to the abactinal area of the disk. The supero-margiual plate 

 adjacent to the median interradial line is broader than long, the dimensions in 

 the example described being length about 3"25 mm., and breadth about 5"75 mm. 

 The abactinal surface of this plate is slightly convex in the median line of 

 breadth. The entire margin of the plate is surrounded by a very narrow 

 depressed border with very minute punctations, closely crowded and uniserially 

 disposed near the inner edge of the border, upon which a small miliary granulation 

 was previously borne. The general superficies of the plate is covered with minute 

 punctations irregularly disposed. The height of the two intermediate supero- 

 marginal plates as seen in the lateral view of the margin (PL XIV, fig. 5 b) is 

 scarcely half their length, and is less than half the height of the underlying infero- 

 marginal plates. 



The ultimate paired plate is very much larger than the small intermediate 

 plate just described, being nearly three times as long, the actual measurement 

 being about 9*25 mm. in the example under notice. It is of a peculiar form, being 

 shaped somewhat like an irregularly formed elytron of an insect as seen from 

 above, the proximal margin being truncate where it joins the companion inter- 

 mediate plate, and the distal extremity obtusely rounded (PL XIV, fig. 5 c). At 

 a point situated three-fourths of the distance from the proximal to the distal 

 extremity rises an abrupt truncate teat-like eminence. The peculiar form of the 

 plate as seen in the lateral view of the margin and the character of the eminence 

 just described will be better appreciated by reference to PL XIV, fig. 5 d, than by 

 verbal description. The superficies of the ultimate plate is studded with rather 

 widely spaced punctations disposed in groups, which do not extend over the whole 

 of the area which falls in the lateral wall of the disk. As seen in the marginal 

 view of the test the ultimate is very much higher than the intermediate marginal 

 plates (see PL XIV, fig. 5 b). 



The odd terminal plate is unknown to me, no trace being preserved in the 

 example under notice. 



In like manner the whole of the abactinal plating within the boundary of the 

 supero-marginal plates has been removed, excepting only a few isolated fragments 

 of plates out of position. 



The infero-marginal plates are large and high. Four are preserved between 

 the median interradial line and the extremity, but the series is incomplete, 

 probably one or more being wanting at the distal end of the series. This would 

 increase the number eight now preserved on the whole side to ten or perhaps 

 twelve. The two infero-marginal plates on each side of the median interradial 



