PROMOPAL^ASTER ELTZ^. 97 



stage or as an individual variation which recapitulates ancestral characters more 

 than is usual. 



The specimen is much smaller than the type. The apical surface is figured. 

 It is seen that the arrangement of the ossicles is much more regular than that in 

 the larger specimens. The radialia retain their characteristic shape (Text-fig. 57) 

 much more than do the radialia of the type, and the supero-marginalia are larger 

 and more distinct. Again, the intermarginalia are fewer. The oral surface is not 

 so distinct, but nevertheless the interradial areas can be seen. These show the 

 odontophor in the same position as that in the type. The groove is 

 closed and the ambulacralia consequently hidden from oral view. Some of the 

 disc-plates, however, have fallen away from the apical surface and exposed long 

 thin ambulacralia exactly as in the type (see PI. IV, fig. 1). 



57 



58 



Textfig. 57 (on left).— Diagram of apical surface of young form of Promopalceaster elizce (based on 



D. 26c). X 4. 

 Text-fig. 58 (on right).— Outline drawing of a portion of the apical surface of PromopalcEaster elizte 



(based on D. 26f). x 6. 



Ornament. — The ornament is of a fine pustulose character. The large spines, 

 so characteristic of very many of the American species of Promopalseaster, appear to 

 be absent except on the circlet already described. It is to be noticed that a similar 

 fine pustulose ornament is present on the infero-marginalia of American species, 

 e.g. P. exsadptm (Schuchert, 85, pi. xx, fig. 2). The large spines of F. chjeri 

 (Schuchert, pi. xx, fig. 6) are situate upon a perforate pustulose elevation very 

 like that figured here, Text-fig. 33, p. QQ>. 



Measurements. — D. 215 and D. 215c, R : r : : 29 mm. : 7 mm. Width of arm 

 at base is 7 mm. 



D. 26 and D. 26c, R : r : : 15 mm. (at least) : 4"8 mm. Width of arm at base 

 is 5 mm. 



Horizon and LocaUtij. — Upper Ordovician (Ashgillian) of Grirvan, A.yrshire, 

 •Scotland. 



13 



