CRINOIDEA. 63 



Interbrachials in lateral areas three, uniserially arranged; in anal area six, irregu- 

 larly arranged. 



Tegmen low, slightly convex, all plates conforming in outline to generic plan; sur- 

 face papilose, conforming to general curvature. 



In form and ornamentation this species resembles Stereocrinus triangulatus Barris, 

 but differs from it in having but one secondary system of ridges, rugose ornamenta- 

 tion, less pronounced neural ridge, low curvature of tegmen and tegmenals, deeper 

 interambulacral, interbrachial, and aboral depressions, and in the much smaller size 

 of the basals, and proximal columnals. 



Occurrence — Mineola limestone of Ralls County. 



Collection — Geological Department of the University of Missouri. Specimen No. 

 3207. 



Stereocrinus springeri n. sp. 



Plate 7, figures 1-3. 



Calyx of medium size, from less than 1.5 to nearly 2 times as wide as high; orally 

 elevated, aborally flattened; aboral flattening including RR. I Ax at angle of 40 with 

 sides above it nearly vertical. Arm bases directed laterally, not markedly protuberant. 

 Tegmen elevated, convex, ambulacral areas elevated gradually on approaching arms; 

 interambulacrals relatively depressed only; separated from interbrachials by a sharp 

 horizontal ridge formed at the bend of the inflexed II nPr 2 ; interbrachials not depressed. 

 Cup ornamented by ridges; three primary and one secondary; neural ridge not accen- 

 tuated; all ridges rugose and broken up into bold, angular bars and nodes, uniting in 

 various ways to form "graphic" figures. Sutures indistinct and not incised between 

 ridges. Tegmenals nodose, barred or tumid depending upon general outline of the plates. 



Basals 3, forming a very shallow funnel, partially concealed by columnals. Axial, 

 canal small, quinquelobate, about 1/4 the diameter of the base. Proximal columnals un- 

 known. 



Primaxials as large or larger than radials. IIBr 2 cuneiform, IIBr 3 et seq., biserially 

 arranged. Arms bifurcating once, all IIBr pinnulate and incorporated to IIBrs. Free 

 portion of nP lost, incorporated pinnular canals closed. 



Interbrachials in lateral areas 4, in anal interray 3 or 4, all uniserially arranged; 

 iIBr 4 inflexed forming rim of tegmen. 



Tegmen high, convex, all plates conforming in outline to generic plan, surface 

 of plates nodose, ridged, or tumid depending upon the plate form. Surface of paired 

 ilAmb granulose. 



This species resembles S. triangulatus Barris in general form but differs markedly 

 from it in ornamentation and number of ilBr. From S. moori Branson and Wilson it 

 differs in the bold angularity of its broken ridges, in a general lack of depressions and 

 in surface sculpture of the tegmenal plates. 



Occurrence — -Abundant at one horizon of the Mineola near Spalding in Ralls County. 

 Exfoliated specimens, seeming to belong to this species, are abundant in the Mineola 

 of Montgomery County. 



Stereocrinus vandiveri n. sp. 



Plate 7, figures 6-8. 



Calyx of medium size, 1.5 times as wide as high, greatest width at apices of I Axs, 

 curving inward toward arm bases; orally flattened, aborally depressed. Arm bases 

 directed obliquely upward, not markedly protuberant. Tegmen very low, 1/3 height 

 of calyx, ambulacral areas not elevated, interambulacrals but slightly depressed, meet- 

 ing slightly depressed interbrachials. Cup ornamented by ridges, three primary and 

 one incomplete secondary; neural ridge accentuated; all ridges low, rounded, and 



