FOSSILS OF THE NIAGARA GROUP. 373 



tally from the column. First radial plates large, second radials 

 hexagonal, much wider than high ; third radials broadly pentangular, 

 supporting on each upper sloping side a series of four supraradials ; 

 the upper one of which is a bifurcating plate, and supports on the 

 upper oblong sloping edges a series of arm plates ; giving eight arms 

 to each ray, so far as determined. First interradial plate large, six 

 or seven sided, with two smaller plates in the second range, three 

 in the third, and several small polygonal plates above, filling the 

 interbrachial spaces and connecting with the dome plates. Anal 

 series unknown. Dome near the base, composed of small polygonal 

 plates, gradually increasing in size towards the proboscis ; the dome 

 is strongly lobed, and the depressions correspond with the inter- 

 brachial spaces. Surface of calyx plates marked by a single set of 

 strong radiating ridges, which connect at the sutures with those 

 of the adjoining plates ; the interspaces occupied by one or more 

 small round nodes, which are sometimes confluent. The ridge along 

 the radial series is much the strongest, and forms a node on the 

 centre of each plate.. The dome plates are marked by similar, but 

 less distinct lines, and a small round node on the centre of each 

 plate. 



This species differs from G. clecadactijlus {Palaeontology Netv YorJi, Vol. 

 i, p. 281, Plates Ixxvii and Ixxviii) in the larger size ; the shortness of 

 the base; the very large dome, and strong proboscis; as well as in the 

 surface marking and greater number of arms. 



Geological Formation and Locality. — In limestone of the age of the 

 Niagara group, Racine, Wisconsin. 



Gltptoorinus armosus (McChesney). 



PLATE X, FIG. 11. 



Glyptocrinus siphonatiis, UALh. Rep. Progress Geol. Survey Wisconsin for 1860, p. 22. 1861. 

 G. siphonatus, 20th Report St. Cab., first edition; rectiiiecl in description of plates. 



Eucdyptocrinus armosus, McChesuet. New Palseozoic Fossils, etc., p. 95. Feb., 1861. 



Body large, broadly obovate, the greatest width being above the origin 

 of the arms ; calyx narrow below, spreading gradually to the bases of 

 the arms ; dome inflated on the anterior (?) side. Arms rising from 

 the body in pairs with deep constrictions between ; arrangement and 

 forms of plates of calyx not fully determined ; those of the dome 

 are small and polygonal. 



