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440 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Lobocrinus equibrachiatus (McCuusyey). 
Plate X XIX. Figs. Sa, b, and Plate XLVI. Figs. 6a, 6. 
1860. Actinocrinus equibrachiatus — McCuusney; New Paloz. Foss., p. 25. 
1867. Actinocrinus equibrachiatus —McCursyey ; Trans. Chic. Acad. Sci., p. 18, Plate 4, Figs. 2 and 5. 
1873. Batocrinus equibrachiatus — Mxrxx and Wortuun; Geol. Rep. Illinois, Vol. V., p. 868. 
1881. Batocrinus equibrachiatus — W. and Sp. ; Revision Paleocr., Part II., p. 165. 
Intermediate between Hutrochocrinus Lover and Lobocrinus pyriformis ; 
differing from the former in the much broader base, and. in having the 
arm bases directed upwards and arranged in groups; from L. pyrifornis 
in the less elongate calyx, in the depressed form of the ventral disk, the 
comparatively longer arms, and in the shorter and more slender anal tube; 
and from both in being decidedly lobed between the rays. Calyx as high as 
wide; the dorsal cup one third higher than the ventral disk, broadly trun- 
cated at the base, the sides concave, gradually widening to the top of the 
first costals, thence rapidly spreading to the arm facets, which are directed 
upward. Plates of the dorsal cup perfectly flat and smooth, those of the 
ventral disk more or less convex. 
Basals forming a nearly cylindrical cup, more than twice as wide as high; 
interbasal sutures indistinct. Radials nearly as long as wide, the upper end 
a little wider. First costals quadrangular, once and a half as wide as long; 
the second fully twice as wide as long, heptangular; their upper angles 
obtuse. Distichals 2 X 2, the second axillary and larger than the other 
brachials ; followed by a single row of palmars, which support the arms. 
Arm openings arranged in groups of two, the interspaces larger between the 
main rays than between their subdivisions. Arms twenty, of moderate size 
and length, frequently infolding at the top, which makes them appear 
shorter than they really are. Interbrachials from five to nine, generally 
continuous with the interambulacral plates at all sides, but always at the pos- 
terior side. Anal interradius composed of ten to fourteen pieces; the anal 
plate higher than the radials ; followed by three ranges of three plates each, 
and a few narrow pieces interposed between the arm bases. Ventral disk 
depressed conical, the plates rather large and of almost equal size. Anal 
tube nearly central, composed of tumid plates. 
Horizon and Locality. —Lower part of the Upper Burlington limestone, 
Burlington, Iowa. 
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