120 



FOSSIL ASTEROIDEA. 



(B) 



TEXT-FIQ. 27. 



B. Without spine-pits. 



TEXT-FIG. 29. 



TEXT-FIG. 28. 



3. Spine-pits fine. 8. Boysi. Text-fig. 

 27, (A) outer view of marginal, (B) 

 interior view of marginal. 



1. Maximum size about 7 mm. S. coro- 



natus. Text-fig. 28. 



2. Maximum size about 2'5 mm. S. 



squamatus. 



3. Maximum size about 2'5 mm. S. 



pistilliferus. Text-fig. 29. 

 N.B. It is impossible to distinguish 

 isolated marginalia of these two species. 

 Compare V, 3 (p. 121). 



y. The collector may also come into possession of the following plates : 



\ 



1. Large triangular plates having the characteristic ornament of Metopaster. 

 These are the ultimate supero-marginalia which characterise the genus. See e. g. 

 PI. XVI, fig. 2 a. 



2. Large hemispherical plates with a flattened base. These are met with in 



the following species : 



A. With spine-pits. 



Staurander aster bulbiferus, S. Boysi, 

 and ? S. bipunetatus. These are 

 distinguished from one another 

 by their spine-pits, which are of the 

 same character as those met with 

 in the marginalia. Text-fig. 30= 

 a primary inter-radial of S. bulbi- 

 ferus. 



B. Without spine-pits. 



Pycinaster senonensis, distinguished by 

 the smooth surface, PI. XXIX, 

 fig. 6. 



Arthraster Dixoni, distinguished by the 

 rugose surface, PL XXIX, fig. 11. 



TEXT-FIG. 30. 



