A treatise on zoology . s pronounced ; 10-20 respiratorypores characteristic (Fig. XLV. 2), but doubtful in Dizygocrinus and verydoubtful in Hyijerocrinus; stem round, usually stout, with small pent-agonal lumen. The family is confined to the Lower Carboniferousrocks of central N. America, where it flourished exuberantly alongwith the parallel family Coelocrinidae. Batocrinus came first (Kinder-hook) and went last (St. Louis) ; the rest are confined to Burlingtonand Keokuk Groups. Genera—Batocrinus^ Casseday (1854 ; em. Sp., 1897), has 1-3 iBr separated from iAmb by IIIBr; 18-26short arm-r
A treatise on zoology . s pronounced ; 10-20 respiratorypores characteristic (Fig. XLV. 2), but doubtful in Dizygocrinus and verydoubtful in Hyijerocrinus; stem round, usually stout, with small pent-agonal lumen. The family is confined to the Lower Carboniferousrocks of central N. America, where it flourished exuberantly alongwith the parallel family Coelocrinidae. Batocrinus came first (Kinder-hook) and went last (St. Louis) ; the rest are confined to Burlingtonand Keokuk Groups. Genera—Batocrinus^ Casseday (1854 ; em. Sp., 1897), has 1-3 iBr separated from iAmb by IIIBr; 18-26short arm-rami set regularly round periphery (Fig. LXXXIL). Eretmo-crinus, Lyon & Casseday (1859 ; W. & Sp., 1897), like Batocrinus^but has 12-26 long paddle-shaped arm-rami, and eccentric anal , Ly. & Cass. (1860, W. & Sp., 1897), constructed likeBatocrinus^ but converges in outward shape towards , W. & Sp. (1897), 18-40 short rami, set regularly around. Fig. LXXXL Coelocrinus immahirus, fromBrit. Mus. E1773. x 1. 168 THE CRINOIDEA periphery like spokes of a wheel; iBr may or may not join iAmb :illBr often present. Duygorrinus, W, & Sp. (1897), like Eutrocho-crinus, but with rounded calyx, more variable in composition, anal tubeand stem rather slender. Hyperocrinus, Meek & Worthen (1865, asUperocrinus; syn. Lobocrinus^ W. & Sp., 1897); 18-22 free rami, arrangedin arm-groups, separated by iBr which join iAmb ; illBr sometimespresent; lofty tegmen ; respiratory pores unknown. Macrocrmus, Sp. (1897); 12-16 rami, in groups, but not separated by iBrexcept in post. IR ; anal tube tapering ; stem slender ; tegmen coni-cal or hemispherical; respiratory pores, 10. The study of the relationsbetween these genera is a fertile and unappropriated field. Family 7. Periechocrinidae. Batocrinoidea with 3 BB; IBr^hexagonal ; each half-ray contains 1-5 IIBr, and sometimes 2-6 IIIBr ;free arm-rami biserial, usually branching ; iBr num
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