32 



with this species, tliough thej are pressed somewhat out of shape, 

 except in one particular. They have three anibulacral openings to 

 tlie vault, in the ray opposite the azygous area, which gives to eacli 

 uiueteen arms. In a better state of preservation they might show 

 other (lifTcrcnccs. and iii;iy belong to auotlier closely related species. 

 Found l)y K. A. Blair, in the Burlington (iroup. near Sharon, in 

 s )ut|i\v<'stcrM MissDuri. nnd now in the colleeliou of S. A. Miller. 



sTi'.(;AN()('iiiNr.s sii.\U()Ni;.NSis, u. sp. 

 PI'dc II. liij. III. iizi/iiniis si:lt': Jii/. II. iijijiosiiv ricir: Ji;}. 1:', mull. 



Species small. C'aly.x obpyraniitlal, rather liroadly truueated, [)i'n- 

 tagonal as .seen from below or above. Plates thick, nodose, pyram- 

 idal. Cnlunm large, canal small. 



Basals form a short, hexagonal cup, deeply notched at tlie sutures. 

 Plates below somewhat cuneiform. First jjrimary radials rath -r 

 large, nodose, wider than long, three hexa^-oual. two hepiagonal. 

 Second i)rimary radials about two-thirds as l.-irge as the first, sculj)- 

 tured ill like manner, wider than long, lu'.xagoiml. Third primary 

 radials smaller than the second, pentagoiud. axillary and support on 

 each ui)|)er sloping side a single secondary radiid which is axillary, 

 and beyond which the plates are not preserved in our sjjecimens. 

 There do not appear to be more than ten openings to the vault, but 

 they are large and the axillary plates show twenty arms. 



The interradial areas all graduate up into the \ault and over the 

 ambulacra! channels so as to leave no dividing line between the vault 

 and calyx. The regular interradial areas are not uniform. The first 

 jilate is followed in each area by two smaller plates in the second 

 rang!'. In each of two areas there arc two plates in the third range, 

 and in the other areas three x^lates, and these separate the arms aiul 

 unite with plates that may be regarded as vault plates. In the azygous 

 area the iirsl jilate is in liiu' with the tirst primary radials and abont 

 the same size. It is followed by two plates in the second range, 

 three in the third range, three in the fourth range, and three in the 

 tiftli range, that se[)arate the arms. 



The vault is only slightly convex and oidy moderately elevated 

 over the ambulacral canals and bears a subcentral proboscis. Tt is 

 covered with convex and nodose polygonal plates. 



