33 



POTERIOCRINllS AKKEGTARIUS, n. Sp. 



I'litic II'. Fi(j. C, (izi/H'jus siilc ricw, showin<i jxirt oj the proboscis. 



Sjiijcies iiuulium sizo iiiul iiofr consti'lcti'd above the calyx. 

 Calyx obconoidal. Sutures distinct. Surface smooth or finely 

 ,i;i-;iiiiihu;. 



riasals partly brolvcn away from our specimen, but enou.^-h is 

 jireserved to show that tliey foi-ni an (jtjconoidal cup. Sub- 

 i-adials larye aud longer tluui wide. P''irst radials nearly as 

 knii^ as wide, pent ii.i^oual, truncated the entire width above, and 

 separated from the second radials or first brachials by a very 

 sliijhtly gapinf^ suture. Sec^ond radials or first brachials sub- 

 quadrate, as long as wide and slightly constricted in the mid- 

 die. Tiiird I'adials or second brachials a little shorter than the 

 first, V(>i-y slightly constricted in the middle, axillary, and sup- 

 port \\\Hm the u[i|>er sloping sides the free arms. The arms 

 do not bifurcate and there are, tiuu'efore, ten arms in this spe- 

 cies. The arms are long, shuider, aiid composed of a single 

 scries of cuneiform plates that bear small pinnules. The pin- 

 nules are from the inside of the arms so as to allow the arms 

 to come together. 



The azygous plates alternate, as is usual in this genus. The 

 first plate is the largest and rests upon the upper slojiing sides 

 of two subradials, separates th(! first radial on the right from 

 the second azygous plate and is truncated on top by the third 

 azygous plate. The second plate is somewhat smaller than the 

 first, hexagonal, and only slightly truncates a subradial. The 

 azygous area alcove the.se plates is wide and terminates in a 

 wide and long proboscis that, in cnir specimen, extends beyond 

 the parts of the arms which are preserved and appears to have 

 extended beyond the tips of the arms. The proboscis is fluted 

 and punrturi'd with longitudinal rows of pores between the 

 longitudinal sei'ies of plates of which it is couiposed. 



This species is distiuguislied by its general form, structure 

 of the arms and character of the proboscis. 



Found by the late Wm. MeAdanis in the St. Louis Group, at 

 Alton, Illinois, aud now in the collection of Wm. F. E. Gurley. 



