96 FOSSIL ASTEROIDEA. 



magnitude, but also by tlie manner in wliicli the upper surface is turned over so as 

 to make the ossicle P-shaped (compare Text-fig. 23, p. 119). 



Associated with these marginalia are found rounded, smooth ossicles, which are 

 correspondingly large, being as much as 12 mm. in diameter, and Avhich are 

 undoubtedly ossicles from the abactinal surface of the disc. Their size and form 

 (see PI. XXIX, fig. 6) render them liable to be mistaken for ossicles of Stanrander- 

 aster (see p. 125). They do not, however, possess spine-pits, and species of Stavr- 

 anderaster which do not possess spine-pits are very distinct, having nodular abactinal 

 ossicles of a very characteristic appearance (compare S. coronntiis, PL XXIV, fig. 2). 

 There appears therefore to be no douljt that these ossicles should be referred to 

 the genus Pi/cinader, and probably to P. pundatus. The base of the abactinal 

 ossicles of P. augnstatiis is produced, as also in P. crassiis (PL XXIX, fig. 4rt), and 

 quite different from the flattened base of these ossicles. 



Itemarlis. — It might be urged that the differences which separate these ossicles 

 from those ascribed to P. (ingustatus, are not sufiicient Avarrant for a new sj^ecies. 

 I regard the differences, however, given above as important, and though several 

 well-preserved specimens of P. augustattis are known, none approaches the large 

 size which P. pnnctatua nuist have attained. On p. 81, Pentaceros senonensin, 

 Valette, was regarded as probably identical with P. Boi/sii. Examination of the 

 original specimens, which I owe to the courtesy of Dom Aurelien, shows that they 

 belong to four different species : Staurandemster coronalas, 8. argtts, Pi/ciii aster 

 angustatns, and my " Pentaceros ])nnctatns.'' The last species is represented by 

 two dorsal ossicles from Les Clerimois (figs. 1 and 2). With the concurrence of 

 Dom Aurelien, I therefore take the original of his fig. 1 as type. 



Locality and Stratigra'phical Position. — The specimens in the possession of 

 Dr. Blackmore are from Bast Harnham, Wilts., zone of Actinocamax quadratns. 



3. Pi'ciNASTEE CRASSus, n. sp. PI. XXIX, figs. 1, 2, 2 a, o, 3 a, 4, 4 a, 5. 



Specific Cltaractcrs. — Body of large size. Height of marginalia not twice their 

 thickness. Median marginalia smooth. More distal marginalia with prominent 

 mammilations. 



Material. — There are about eight fragmentary specimens of this species in the 

 British Museum (Nat. Hist.). The specimen registered E. 257G (Mantell Coll.) 

 shows considerable portions of the actinal surface, and that registered 35498 

 (Taylor Coll.) the dorsal view of a well-jireserved portion of one arm. Both these 

 arc figured on PL XXIX. Another specimen, registered E. 2028 (Mantell Coll.), 

 shows a portion of the abactinal siu'face of the disc. The other specimens are 



