9 



with the first prhuary ra.Uals and iKjarly as large, it is fol- 

 lowei in the sasoni rani^e by tliree plates, above which there 

 are two plates. One is above the middle plate and the other 

 is to the right of it. 



The vault is modei-ately convex, covered with polygonal 

 spinous plates, and bears a subcentral proboscis. No ovarian 

 pores have been discovered. 



This species is distinguished among the eighteen armed 

 species, by its general form, surface ornamentation, two sec- 

 ondary radials, and by the interradial and azygous areas. 



It was found in the Warsaw (Jroup, at Silem, Indiana, and 

 is now in Ihi' colli'dion i>r ('li;irli'> Ij. h\i.l«'r. 



B.M'OflUNTS STKIJ-lFDIvMllS, 11. sp. 



Plate I, Fig. 13, basal view: Ficj. N. azygous side; Fig. !■'>, 



sum mil. 



Species below medium size, depressed, biturblnate. Calyx 

 broadly rounded below, about three times as wide as high. 

 Ridial ridges slightly defined and each series projecting so as 

 to give it a stellate outline. Ambulacral openings directed up- 

 ward and not visible from a basal view. Plates plane and 

 smooth. 



Basal plates form a low cup, hexagonal, with a slight re- 

 entering angle on the azygous side, diameter one-half gi-eatei- 

 than the diameter of the column. Depression for the attach- 

 ment of the column, moderately concave. First primary ra- 

 dials large, a little wider than long, three hexagonal, two 

 hcptagonal. Second primary radials short, quadrangular, three 

 or four times as wide as long. Thii'd primary radials about 

 one-half larger than the .second, three times as Avide as long, 

 pentagonal, axillary, and. in four rays, bear ujion each upper 

 sloping side two secondary radials. the last ones of which are 

 axillary and bear upon each upper sloping side two tertiary 

 i"idials, which gives to each of these rays four arms. In the 

 ray opposite the azygous area, the third primary radial bears 

 ujjon each upper sloping side three secondary radials, which 

 gives to it two arms. There are, therefore, eighteen arms in 

 this species, and eighteen ambulacral openings to the vault. 



