66 THE DEVONIAN OF MISSOURI. 



il Br irregular, 1, 1, 2, 2, 1. 1; 1, 2, 3, 2, 2, 2, etc.; illBr absent in antero-lateral rays, and 

 irregular in the others; il II Br few or none. 



Tegmen high, convex; "orals," and plates covering ambulacral areas larger than 

 interambulacrals. 



Anal tube excentric, large. 



Column and arms unknown. 



Measurements of the type specimen are: Height of cup 23mm., of tegmen 17 mm., 

 width of base 33 mm., at arm bases 52 mm. 



The holotype of this species is not complete, as the left lateral rays have been broken 

 away but these we have restored in the description. 



Megistocrinus broadheadii closely resembles M. concavus W. & S., (N. Am. Cam. 

 Crin. p. 543, pi. 48, figs. 5a-c), in general configuration, and lack of secondary and 

 tertiary interbrachials, but differs from it the greater divergence and flattening of the 

 cup walls, greater prominence of .the arm bases, wider interradial depressions, larger 

 size of the marginal tegemenals, lower convexity of the calyx plates, and lack of nodes 

 on the "orals" and radial dome plates. 



Occurrence — Mineola limestone, 4 miles south of Montgomery City. The formation 

 may be Callaway. Only a small patch of the rock is exposed, and it contains no diag- 

 nostic fossils. 



Megistocrinus mineolaensis n. sp. 

 Plate 6, figures 2-4. 



Species large. Calyx globose, wider than high; cup bowl shaped, with basals and 

 radials nearly horizontal; tegmen as high as cup, convexity high; plates conforming to 

 curvature of walls, unornamented (?), sutures scarcely visible. Measurements of type 

 specimen, height 43 mm., width at arm bases 56 mm., width of aboral area of flattening 

 30 mm. 



Base hexagonal projecting beyond column; basals ankylosed; width of column facet 

 unknown; axial canal quinquelobate, about 3/8 diameter of basal hexagon. 



All plates in radial cycle hexagonal; radials slightly larger than anal x, 2/3 as high 

 as wide. Primibrachs 2 x5, IBn larger then IAx. Arrangement of intrebrachials above 

 I Ax according to the group plan (see generic description). Primary interbrachials 

 irregular in arrangement; 1, 3, 3, 2, 2, 3; 1, 3, 4, 3, 3, 3; 1, 2, 3, 3, 3, and variable in size 

 but growing progressively smaller from the base up. illBr, irregular, 1, 2, 2, or 1, 2, 1 

 ill I Br also irregular, all interbrachials meeting interambulacrals in slight interradial 

 depression. 



Tegmen high, sloping upward from all sides to base of anal tube; ambulacrals 

 preserved near margin, biserial; ambulacral areas slightly elevated, interambulacrals 

 slightly depressed. Anal tube excentric, 1/3 the diameter in from the back margin, 

 Tegmenals numerous, about 200, irregular in size and form; orals undifferentiated. 



Megistocrinus mineolaensis resembles M. multidecoratus (Barris) in general con- 

 figuration but differs markedly from it in an entire lack of ornamentation, and in having 

 a lower tegmen. 



Occurrence — Mineola of Ralls County. 



Megistocrinus missouriensis n. sp. 



Plate 6, figure 1; plate 8, figures 1-2. 



A large species. Calyx shallow, about three times as wide as high ; tegmen flattened, 

 basals and radials deeply and abruptly depressed; sides expanding rapidly upwards; 

 arm bases elevated; plates strongly convex, margins depressed, sutures inconspicuous. 

 Measurements of type specimen: Height 26 mm , width 66 mm., width of basal con- 

 cavity 20 mm., depth 8 mm. 



