120 



FOSSIL ASTEROIDEA. 



Text-fio. 27. 



c. Without spine-pits. 



Text-fig. 29. 



Text-ho. 28. 



3. Spine-pits fiue. S. Boijsi. 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 25 mm. S. 



squamatus. 



3. Maximum size about 25 mm. 8. 



jnstiUi/erus. Text-fig. 29. 

 N.B. — It is impossible to distinguish 

 isolated marginalia of these two species. 

 Compare V, 3 (p. 121). 



V. — T]t£ collector may also come into possession of tJw following plates : 



1. Large triangular plates liaving the characteristic ornament of Metopastcr. 

 These are the ultimate supero-margiualia 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. 



Stauranderaster hulbiferus, S. Boijsi, 

 and ? S. hijiiiticfatiig. These are 

 distinguished from one another 

 hy 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. hulbi- 

 ferus. 



B. Without spine-pits. 

 Pycinaster senonensig, distinguished by 



the smooth surface, PL XXIX, 

 fig. 6. 

 Arthraslcr Dironl, distinguished by the 

 rugose surface, PI. XXIX, fig. 11. 



Text-fm. 30. 



