110 



FOSSIL OOLITIC ASTERIADtE. 



and sold by him to Professor Buckman, to whose collection it now belongs. In fig. 2 a, 

 the fossil is represented lying on the under side, having the upper surface fully 

 exposed; in fig. 2 /^, a lateral view of the same is given, for the purpose of showing the 

 height and inclination of the marginal plates ; in neither figure has Mr. Bone ventured to 

 delineate the ossicles of the disc. 



Pamily~-ASTROPECTENID^, Muller and TroHchel. 



The species of this family have a stellate body flattened on both sides. The rays are 

 narrow, elongated, and bordered by one or two rows of marginal ossicula. The ventral 

 plates are always spiniferous, and the dorsal, when present, are covered with granules 

 which are more or less so likewise. The narrow ambulacral valleys, have two rows of holes 

 for the passage of tubular feet. The upper surface of the body, between the marginal 

 plates, is covered with paxillse closely set together, and the under surface is crowded wdth 

 short spines arranged in regular rows. 



In the classification of Muller and Troschel this family comprises the genera Astro- 

 peden and Ctenodiscus, which possess a double series of marginal plates, and Luidia, with 

 only a single ventral row of marginal spiniferous ossicula. At (page 48) the reader will 

 find a diagnosis of the genera of this family ; to these I have added the genus Plumaster, 

 an extinct form from the Lias which has many affinities with Luidia. 



Genus— U]YDlk, Forbes. 



Fig. 37. 



Rays elongated, and numerous. Margin provided with a single row of plates, instead 

 of a double row as in Adropeden. These ventral marginal ossicula carry spines, 



as seen in the subjoined figure 

 of the section of a ray of 

 Luidia Senegalensis, where a 

 shows the upper, and b the 

 lower surface. The upper sur- 

 face of the body is covered with 

 small close-set paxillse (a). The 

 ambulacral valleys are narrow, 

 and the suckers biserial (b). 

 Two sets of spines are found on the underside of the ray, the central portion has 

 rows of short, stout spines, and the marginal plates are armed with long recurved spines. 



Portion of a ray of Luidia Senegalensis, M. and T. A, tlie upper; 

 B, the under surface. 



