NO. 1GG4. -i NEW JURASISIV CRINOID^ISl'h'lNaEli. 181 



a marked stellate outline. Conformably to this structure the cirri 

 are directed upward. Interarticular pores extending to the fifth 

 internode. Cirri in whorls of five; round, long, and slender, com- 

 posed of 40 joints or more; the proximal ones relatively short and 

 broad — about one-third as long as wide— tapering rapidly to about 

 half their breadth, and doubling in length in the first 8 or 10 joints, 

 beyond which they continue uniformly about as long as wide to the 

 end; terminal claw not preserved. Angles of stem interradial; cirri 

 radial ; axial canal in stem small, obtusely pentagonal, and apparently 

 interradial in position. 



Cup forming a low cone, without any downward projection of 

 basals or radials. Infrabasals well defined, filling half the diameter 

 of the column facet and entirely covered by the proximal columnal. 

 Basals large, smooth, visible in pentagonal outline, and in full contact 

 exteriorly by their lateral faces; they form a closed ring, not pro- 

 tuberent but flush with the plane of the radials, and about equal to 

 them in height. Radials forming also a ring continuous with basals. 

 Primibrachs two, united by articulation apparently bifascial. Arms 

 simple, or bifurcating once from the sixteenth to the thirtieth IIBr, 

 thus varying from 10 to 20; they are long, slender, with strongly 

 oblique articulating faces, and they extend to upward of 90 brachials. 

 Syzygies at IIBr 3-|-4, and beyond throughout the arm at intervals 

 of about 5 to 10 brachials. Pinnules long, rounded, composed of 

 elongate joints, 15 or more in the distal pinnules, but the number in 

 the proximal ones not observable. Disk unknown. 



Dimensions of mtiiine iniUviduah 



mm. 



Height of crown C.5 



Width of axillary IBr 7 



Height of axillary IBr 5 



Length of cirrns of 40 joints H2 



Length of longest stem preserved 140 



Diameter of stem at second internode 2 



Diameter of stem at tenth internode_l 2-5 



Diameter to height of second internode 1-2.2 



Diameter to height of tenth internode 1-.5. 2 



Diameter of stem to length of longest cirrns 1-17 



Horizon cmd locality. — In the Shirley stage of the uppermost 

 Jurassic. Medicine Bow, and Red Buttes, Wyoming. 



The occurrence at Medicine Bow w^as in a band of argillaceous 

 limestone about 1 inch thick, and it is undoubtedly the remnant of a 

 considerable colony. The upper surface of the layer is filled with 

 disintegrated stem joints and brachials closely cemented together, 

 while toward the lower part the crinoids had been embedded as they 

 perished without much disturbance. Unfortunately the layer was 



