THE CRINOIDEA 167 



The chief feature is the fixed recumbency of the arms, as in some Hexa- 

 crinklae and Acrocrinus ; but differing from those forms in that the 

 pinnules were very close-set, and folded in two rolls over the ventral 

 groove when closed. Except for this and the consequently more solid 

 tegmen, the genus is not far removed from the Carpocrinidae. Ant. R is 

 hexagonal ; r. and 1. ant. RR heptagonal ; r. and 1. post. RR pentagonal. 



FAMILY 5. COELOCRINIDAE. Batocrinoidea with 3 BB ; in each half- 

 ray, 1 or 2 IIBr ; free arms separated by 3 or more iBr in contact with 

 iAmb, 2-4 biserial rami to each ray ; a row of anals in post. IR, sup- 

 porting no tube ; but anus opening marginally from a slight prominence ; 

 tegmen solid, with large 0, esp. post. O ; no respiratory pores known. 

 Genera Coelocrinus, Meek & Worth. (1865-66 ; synn. Sphaerocrinus, M. 

 & W. non Roem. ; Aorocrinus, W. & Sp., 1897), Devonian and Carboni- 

 ferous, N. America, and (?) Devonian, Europe (Fig. LXXXL). 2 or 4 

 rami to each ray, each with independent opening into the theca ; cup extend- 

 ing below arm-bases. Dorycrinus, C. F. Roemer (1854, W. & Sp., 1897), 

 Carboniferous, N. America ; derived from Coelocrinus with convex base ; 

 rami paired, 2 to a single opening ; radial dome-plates of tegmen bear 

 large spines. Agaricocrinus, Hall ex Troost (1858 ; W. & Sp., 1897), 

 Carboniferous, N. America ; derived from Coelocrinus with concave base, 

 that feature being greatly exaggerated so that 

 the cup does not project below the arm-bases ; 

 rami 2-4 in each ray, each with independent 

 opening. FAMILY 6. BATOCRINIDAE. Bato- 

 crinoidea with 3 BB ; each half-ray contains 

 1-5 IIBr, also IIIBr, 1-5, always in adanal 

 series, and sometimes in the rest, but rarely in 

 anterior series ; free arms with 1-4 biserial 

 rami in each ray ; iBr, 1-15, usually uncon- 

 nected with iAmb, except in post. IR, and 

 sometimes separated from them by the brachials 

 there also ; plates in posterior IR 2-19, per- 



' " Coelocrinus immatitrus, from 



haps more ; anal tube long, usually stout, and Brit. Mus. E1773. x j. 

 central ; tegmen solid, with and radial dome- 

 plates usually prominent, post. O always pronounced ; 10-20 respiratory 

 pores characteristic (Fig. XLV. 2), but doubtful in Dizygocrinus and very 

 doubtful in Hyperocrinus ; stem round, usually stout, with small pent- 

 agonal lumen. The family is confined to the Lower Carboniferous 

 rocks of central N. America, where it flourished exuberantly along 

 with the parallel family Coelocrinidae. Batocrinus came first (Kinder- 

 hook) and went last (St. Louis) ; the rest are confined to Burlington 

 and Keokuk Groups. Genera Batocrinus, Casseday (1854 ; em. W. 

 & Sp., 1897), has 1-3 iBr separated from iAmb by IIIBr; 18-26 

 short 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-rarui, and eccentric anal tube. 

 Alloprosallocrinvj, Ly. & Cass. (1860, W. & Sp., 1897), constructed like 

 Batocrinus, but converges in outward shape towards Agaricocrinus. 

 Eutrochocrinus, W. & Sp. (1897), 18-40 short rami, set regularly around 



