MILWAUKEE CRIXOIDS. 121 



depressed convex or nearly flat. 2. In its more strongly nodose 

 plates, the nodes in this species being nearly as thick at their 

 bases as the width of the plate of which they are a part, with 

 the sides of the nodes subparallel or even in some cases diverg- 

 ing outward, making the node somewhat club-shaped, being 

 thicker towards its extremity than at its base, while in M. no- 

 dosiis the sides of the nodes alwa>'s converge outwards. 3. In 

 the presence of three plates rather than two in the second row 

 of interbrachials on the posterior side. 



Melocrinus milwaukensis n. sp. 

 (PI. XIV. Fig. 7.) 



Calyx pyriform, truncated at the base, sides slightly convex 

 from the tops of the basals to the arm openings. Cross-section, 

 as seen from above, obscurely pentagonal. Greatest diameter 

 at the arm bases. All the plates of the dorsal cup convex or 

 ornamented with low, broad, central nodes. 



Basals four, moderately nodose, not projecting far beyond the 

 column. Radials large, heptagonal and hexagonal. First cos- 

 tals hexagonal, smaller than the radials, second costals pentag- 

 onal or heptagonal, smaller than the first. Distichals much 

 smaller than the last costals, the second or third pair becoming 

 free. First interbrachials in the four regular interradial areas, 

 hexagonal, as large as the first costals, followed b}' two smaller 

 plates in the second and three still smaller ones in third row, 

 these being followed b}' small plates which lead up to the inter- 

 radial plates of the vault. In the posterior interradius the first 

 or anal plate is similar in size to the first interbrachials of the other 

 sides, but is heptagonal in form, being followed by three plates 

 in the second row. 



Ventral disk depressed convex or nearly flat, composed of 

 small polygonal nodose plates of nearly equal size ; marked by 

 more or less prominent ambulacral ridges extending from the 

 arm openings towards the center ; and surmounted by a sub- 

 central proboscis whose height cannot be determined. 



Remarks. This species with its associated variety differs from 



