tSTEROtD&A 01 NORTH I'M nn KM> ADJACENT « M I l;~ I i-HKlc 



■iia forma 



Forma POI.l I Ml I \ \ . rrlll 



Plate 30, Figure 5, So, Plate 81, Figure 1, la If; Plate I, 40 



too polythda Vkbbii i . 1909, 



Tin- forma comporte itself more like a conventionaJ species than does 

 When approximately typical (pi. 39, and 10 it is very i-n.-ih recognized bj reason of 

 the ten large ratlicr widely separated uprighl abaotina] Bpines, It is connected with 

 forma iiri rvata by numerous intermediate forms of which the type of net tata is oi 



/' • i :.. medium-sized, 6-rayed form, with rather slender to moder- 



ate^ stout, depressed to well arched rays and Bmall ilisk: abactina] Burface of i 

 with G to 30 large, conical or acorn-shaped spines, typically solitary, "r in t\M>~, or 



rionally more, borne on convex plates much larger than the others, and nr 



