112 



CATALOGUE OF THE BLASTOIDEA. 



each interradius. But it shows the relation of the spiracles extremely well. They 

 are very minute slits at the sides of the knife-like central ends of the deltoids, and 

 often almost as inconspicuous as in Pentremitidea Paillettei and P. Lusitanica 

 (PI. IV. figs. 8, 10, 12) ; but they are occasionally rather larger, as shown in our 

 diagram (Fig. VII. B). 



Fig. VII. 



Diagrams of Troostocrinus Reinwardti. A. The anal side. B. Summit view. The 

 radio-deltoid sutures are shown by rather darker lines. 



It may be well for us to state here that acting upon information supplied to us by 

 Mr. Wachsmuth since pages 36 & 37 were printed, and also by his desire, we have 

 decided to restrict the generic name Troostocrinus to T. Reinwardti, which has the 

 anal deltoid visible externally and a single anal spiracle (Fig. VII.); while we 

 propose to take Pentremites lineatus, Shumard, as the type of a new genus Meta- 

 blastus which has all its deltoids alike and the two posterior spiracles distinct 

 from the anus (PI. III. figs. 14, 15). 



