532 P. H. Carpenter — Notes on Oreaster hulhiferus. 



down the original arms. They gradually decrease and separate the 

 origins of two series of transversely oblong, over-lapping, lobed, 

 bordered, and centrally punctated plates, which alternate at the sides 

 with a smaller row ; and these are succeeded by smaller ones. 



•' The extremity of each ray is swollen into a pyriform shape, 

 forming an eye-protecting apparatus. The summit of this is formed 

 by very large, convex, subglobose, punctated plates, which correspond 

 to those at the origin of the ray. These alternate at the sides with 

 five very large, nearly flat, oblong, similarly' ornamented plates, 

 which articulate with others half their size, corresponding to the 

 inferior row ; beneath them are others much smaller, which (with 

 minute ossicles) border the avenue, corresponding to the under row. 

 All the plates of the bulbous terminations of the arms are much 

 larger than those to which they correspond, except the last." 



The subjoined woodcut will serve to show (1) the upper and (2) 

 under side of an arm of Oreaster hulhiferus, Forbes : — 



Arm of Oreaster bulbiferus, Forbes, 1 Upper, 2 Under side, [a) ambulacra. 



" This is one of the handsomest and most curious of all the fossil 

 Star-fishes. It is rather rare, and seldom seen perfect. One or two 

 living species of Oreaster have a similar, but not equal, development 

 of plates at the extremities of the rays." The specimen figured by 

 Professor Forbes in Dixon's Geology of Sussex is from Northfleet, 

 , Kent ; another specimen has been obtained from Sussex. The pair 

 figured in our Plate were obtained from the Upper Chalk of 

 Bromley, Kent, and are preserved in the British Museum of Natural 

 History. They show the large tubercles of the dorsal surface very 

 clearly, and in one of them the madreporic plate (m. p.) is also 

 visible. The peculiar shape of the rays is well shown in the 

 accompanying diagrams of their upper and under sides. The latter 

 may be advantageously compared with a figure given by Mr. Agassiz 

 of the same parts in the recent Pentaceros reticulatus of the North 

 American coasts. ^ 



^ Zoc. cit. pi. xvi. fig. 4. 



