ECHIXODERMATA PELMATOZOA 



SUB-KINGDOM III 



united by sutures. Orals asymmetrical ; ambulacra bifurcating once or twice within 

 the calyx, and roofed by two roics of very regularly arranged covering pieces ; a few 

 inter ambulacrals also present. Anus eccentric, placed at the end of a tube. Arms 

 uniserial, dichotomising at short intervals throughout their entire length. Pinnules 

 unknown. Column round, strong, the distal end formed into a thick root. Silurian. 



This family embraces the genera Crotalocrinus, Austin (Anthocrinus, Mtiller), 

 (Fig. 254), and Enallocrinus, d'Orb., both of which are found in the Silurian of 

 Gottland and England. 



The arms of the same ray are laterally united in Crotalocrinus throughout 



FIG. 254. 



A, Crotalocrinus pulcher, Rising. (Anthocrinus Loveni, Miiller). Silurian ; Gottland. Crown with folded 

 arms. B, Portion of stem. C, Cross-section of four contiguous arm-ossicles of the network. I), 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 ambulacra] furrows. E, Tegmen of C. rugosits, Miller (after 

 Angelin). 



their entire length, so as to resemble five broad, reticulate leaflets ; Avhile 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 3. FISTULATA. Wachsmuth and Springer. 

 (Inadunata fistulata, W. and Sp. ; Cyathocrinacea, Neumayr.) 



All plates of the dorsal cup united by close suture. Jtadials 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 Die 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, 





