86 The Ohio Journal of Science [Vol. XIX, No. 1, 



Plate IX. 



Fig. 52. Outline of oral plates and food grooves of A. austini, showing the union 



of grooves 1 and 2, and that of grooves 4 and 5 into the primitive trimeric 



arrangement. The large plates of the anal pyramid are 7 in number. 



Oral plates not united into the usual three. 

 Fig. 53. Oral plates and food grooves of a specimen of A . pileus showing elements 



of Plate P. 

 Fig. 54. Oral plates and food grooves of A. rectiradiatus, Shideler, diagram from 



small specimen. Fig. 29, PI. V. The dotted lines indicate the probable 



number of plates forming the oral plates. 

 Fig. 55. Several diagrams of plate systems of oral side of minute specimens of 



A. austini var lawshe. 

 Fig. 56. Oral plates and rays 4 and 5 as shown in large specimen of A . rectiradiatus. 



Small arrow shows probable location of hydropore. 



