150 ECHINODERMATA—PELMATOZOA SUB-KINGDOM III 
united by sutures. Orals asymmetrical ; ambulacra bifurcating once or twice within 
the calyx, and roofed by two rows of very regularly arranged covering pieces; a few 
interambulacrals also present. Anus eccentric, placed at the end cf a tube. Arms 
uniserial, dichotomising at short intervals throughout thei entire length.  Pinnules 
unknown. Column round, strong, the distal end formed into a thick root. Silurian. 
This family embraces the genera Crotalocrinus, Austin (Anthocrinus, Miiller), 
(Fig. 254), and Enallocrinus, @Orb., both of which are found in the Silurian of 
Gottland and England. 
The arms of the same ray are laterally united in Crotulocrinus throughout 

Fic. 254. 
A, Crotalocrinus pulcher, Hising. (Anthocrinus Loveni, Muller). Silurian; Gottland. Crown with folded 
arms. B, Portion of stem. (, Cross-section of four contiguous arm-ossicles of the network. J), Dorsal aspect 
of arm-plates, showing their intimate union ; those above the two rows figured have been broken away so as to 
expose the side-pieces and covering plates of the ambulacral furrows. /, Teginen of C. rugosus, Miller (after 
Angelin). 
their entire length, so as to resemble five broad, reticulate leaflets ; while those 
of Enallocrinus are united for a certain distance only, and then become free. 
The arms in both forms were capable of being stretched out horizontally on the 
same level with the tegmen. 
Order 38. FISTULATA, Wachsmuth and Springer. 
(Inadunata fistulata, W. and Sp. ; Cyathocrinacea, Neumayr:) 
All plates of the dorsal cup united by close suture. Ladials bisected or simple. 
Anal plate (IRA) generally, and radianal (RA) frequently represented ; the former 
resting upon the truncated upper face of the posterior basal, the latter situated to the 
right of the IRA, and within the angle formed by the posterior and postero-lateral 
basals. Interradials proper not represented. Tegmen greatly extended at the posterior 
side to form an elongate or balloon-shaped sac. Ambulacra tegminal, lined by side- 
plates, and roofed over by small covering pieces. Mouth eccentric and subtegminal, 
