20 



First primary radials wider than long, verj' tumid, three 

 hexagonal, two heptagonal. Second primary radials small, 

 quadrangular, three or four times as wide as long. Third 

 primary radials twice as large as the second, ijentagonal, ax- 

 illary, and support on each upper sloping side two secondary 

 radials, the last of which are axillary and support on each 

 upper sloping side two tertiary radials, except in the arms 

 adjoining the azygous area where there are three, which ar- 

 rangement gives to each ray four arms. There are, therefore, 

 twenty arms in this species. 



None of the interradial areas connect with the vault. There 

 is a single plate in the regular interradial area, on the right 

 of the azygous area, and two plates in each of the other regu- 

 lar interradial areas, the first one large, the second one smaller. 

 Azygous area subovate and contains eight plates. Tlie first 

 one is in line with the first primary radials and fully as large. 

 It is followed by three plates in the second range, three plates 

 in the third range, and one small plate in the fourth range, 

 which is cut ott' from the vault by the Ihii'd tertiary radials. 



The vault is convex and covered with tumid ])()lyg()ual jilates. 

 and bears a rather large subcentral proboscis. 



This species is distinguished from all other twenty-armed 

 sjjecies by the third tertiaiy radials adjoining the azygous area 

 and by the form of the azygous area and the number of plates 

 it contains. It is unnec'essury to carry the comparison furthei-. 



Found in the Biu'lington Ciroup, at Sedalia, Missouri, and 

 now in the collection of F. A. Sampson. 



BATOCRiNi's sprnius. n. .sp. 



Plate II, Fig. 7, one of the azijgous sides; Fie/. 8, the other azijcjous 

 side; Fig. !f, opposite vieir. 



The specimen to whicli we have attached the nanu> al)ove is 

 medium size, robust, has only four ray.s, eighteen arms and 

 two azygous areas. If it is aljnoiinal, we are unable to refer 

 it to any descrilj<>d sjiecies, und as it is extraordinary and 

 bears no evidence of ev(>r ha\ing been injured, we thinlc we 

 are justified in giving it a name and describing it. 



It is biturbinate. Plates convex oi- tumid. 



