80 FOSSIL ASTEROIDEA. 



2. Pentaceeos Boysii, Forbes, sp. PI. XXII, figs. 4, A a, 4h, 4c; PI. XXIII, 



figs. 1,1 a, lb; PI. XXVI, figs. 2, 2 a, 2 b. 



Oeeaster Botsii, Forhes, 1848. Mem. Geol. Surv. G-t. Brit., vol. ii, p. 468. 



— — Forbes, 1850. In Dixon's Geology and Fossils of the Tertiary 



and Cretaceous Formations of Sussex, p. 328, pi. xxi, 

 fig. 6. 



— — Dujardin et Hupi^, 1862. Hist. Nat. Zooph. Echin. (Suites a 



Buffon), p. 389. 



— — Forbes, 1878. lu Dixon's Geology of Sussex (new edition, 



Jones), pp. 362, 370, pi. xxi, fig. 6. 



Si^rcific Characters. — The primary radialia and interradialia are large liemi- 

 spheroid pimctate tubercles. R : r ; : 80 mm. : 18 mm. Rajs well produced, steep- 

 sided, almost square in section, and tapering gradually to the extremity. Onlj- a 

 few of the plates of the disc enter the base of the arm. Supero- and infero- 

 marginal plates adjunct, the intermarginalia being represented only by a few 

 scattered granules. 



Material. — The type specimen was said by Forbes (1848) to be in the collection 

 of the Marquess of Northampton. The specimen figured and described in Dixon's 

 * Geology of Sussex ' (see reference) was said by Forbes to have been " discovered 

 by Major Boys and formed part of his interesting collection." This statement 

 does not preclude the hypothesis tliat the specimen figured was also the type 

 specimen. Neither specimen (if there were two) can now be traced. The following- 

 description is based chiefly on a specimen in the Sedgwick Museum, Cambridge 

 (PL XXVI, fig. 2), which shows the actinal surface of the arms and a portion 

 of the disc. It is supplemented by reference to a less nearly perfect specimen 

 preserved in the British Museum of Natural Histoiy (J. Simmons' Coll., 4G600), 

 which presents views of isolated rays (PI. XXII, fig. 4), and an isolated ray seen 

 from the dorsal surface (PI. XXIII, fig. 1) in the same museum (Dixon Coll., 48083). 



Bescription. — The disc is covered with a number of rounded or irregularly- 

 shaped plates. A circlet of large tubercles is very distinct and characteristic of the 

 species. These tubercles are hemispherical and not so swollen as those of 

 P. hiilbifenis. They are smooth, and possess a fine distinct ornament, thus 

 distinguishing them from the circlet of P. coronattts. Their diameter is about 

 8'5 mm., and they seem to be arranged radially and interradially, making a total 

 of ten. The madreporite was figured by Forbes. It is roughly triangular in shape. 



