AtfD ITS RELATIONS TO RECENT COA1A.TUL.E. 201 



nearly horizontal ridge (PL X. fig. 10); but in Ant. decameros, as 

 1 will call the Nattheim specimen, the ligament-fossae have a 

 convex upper border (PI. X. fig. 11), behind and inside which are 

 the muscle-plates. Consequently these stand out much more in- 

 dependently of the ligament-pits than those of Ant. Tessoni do. 



Diameter 8| millims. Height 7| millims. ; radials 3| millims. 



X. — The "Woodwardian Museum contains three specimens, all 

 from Nattheim, of another small Antedon, which differs considerably 

 from either of the species just described. The radial pentagon is 

 much depressed, as in Ant. complanata (PL IX. fig. 9 a), and its ex- 

 ternal surface slopes rapidly downwards and inwards until it meets 

 the low centrodorsal. The latter is thus of much less diameter 

 than the radial pentagon, especially in the specimen represented in 

 PI. X. fig. 13. Neither of the three (PI. X. figs. 12, 13) show 

 external basals ; and in this respect they differ from certain some- 

 what similar forms that have been already described elsewhere. 

 Among these are Ant. Picteti and Ant. infracretacea of de Loriol, 

 already referred to as having scarcely visible basals. The first 

 of these, from the Etage Valangien of Switzerland, differs from 

 the "Woodwardian specimens {Ant. depressa) in being a good deal 

 smaller, and in the somewhat different proportions of the radials, 

 though the same general features appear in both. Besides A. 

 Picteti has only ten cirrhi or even fewer ; while there may be three 

 rows of sockets in Ant. depressa (PI. X. fig. 12). This last has a 

 general resemblance to fig. 35 on Taf. 96 of Quenstedt's ' Encri- 

 niden,' which he calls the young of Ant. costata ; while, except 

 for the absence of basals and of a transverse ridge on the concave 

 lower surface of the centrodorsal, fig. 13 on PI. X. is not un- 

 like Quenstedt's figures of Ant. sigillata (tab. 96. figs. 49, 50). 

 The original has only one row of cirrhus-sockets of the usual 

 Solanocrinus character, viz. oval-oblong in shape with a trans- 

 verse articular ridge pierced by the opening of the cirrhus-canal. 

 There is, however, no distinct indication of this in either of 

 Quenstedt's figures, which may be due either to the imperfect 

 preservation of his specimens or to their immaturity. 



Diameter of largest specimen 7 millims. Height 4^ millims. ; 

 radials 1\ millims. 



SI. — The designation sigillata has been given by Quenstedt to 

 those rare specimens which show a perforated articular facet on the 

 lower surface of the centrodorsal, thus retaining, as suggested by 

 him, more or less permanent traces of their larval condition. 



