164 



ECHINODERMATA PELMATOZOA 



SUB-KINGDOM III 



fused with the top stem-joint. The posterior B larger than the rest, and 

 truncated or excavated at its upper face. Costals three to six, decreasing in 

 size upwards ; the two lower ones laterally united by a few large inter- 

 brachials. The posterior interray markedly different from the others ; 

 composed of a large number of exceedingly minute pieces, which enclose a 

 longitudinal row of six to twelve moderately small, quadrangular, anal plates, 

 supporting a small tube at the upper end. Tegmen formed by small, almost 

 microscopic limestone particles, and extremely flexible. Arms ten, giving 

 off clusters of armlets either from the sides at intervals, or only at their 

 upper ends. Middle Sub-Carboniferous ; North America and England. 



Forbesiocrinus (de Kon. and le Hon), Hall. Differs from Taxocrinus in the 

 construction of the anal area. IRA and EA both represented. Inter- 



FKJ. 270. 



Ichthyocrinus lacris, 

 Conrad. Perfect 

 crown. Silurian 

 (Niagara Group); 

 Lockport, New York 

 (after Hall). 



FIG. 272. 



Taxocrinus intermedium, 

 W. and Sp. (after Wachs- 

 inutli and Springer). 



FIG. 271. 



Lecanocrinus Sill- 

 ingsi, Aug. Silurian; 

 Gottland. a, Calyx, 

 seen from one side 

 (right and left re- 

 versed) ; I, Crown, 

 seen from the anal 

 side (after Angelin). 



Taxocrinus Meeki, Hall sp. 

 Perfect crown. Sub-Carbonifer- 

 ous ; Crawfordsville, Ind. 



brachials very numerous, arranged in some cases in twelve or more rows. 

 Arms long, bifurcating, rather closely apposed, and with infolding tips. 

 Sub-Carboniferous ; North America and Europe. 



^Mespilocrinus, de Kon. and le Hon. Crown small and unsymmetrical, 

 owing to the dextrorse arrangement of the arms. Posterior B truncated, 

 and supporting a small IRA, which is the only supplementary plate of the 

 dorsal cup. Costals and distichals two, followed by a very few free arm- 

 plates. Arms very short, closely folded, and inclining to the right, owing to 

 the cuneate form of lower brachials. Sub-Carboniferous; North America 

 and Europe. 



Homalocrinus, Anisocrinus, Calpiocrinus, Cyrtidocrinus, Pycnosaccus, Aug. ; 

 Lithocrinus, W. and Sp. Silurian, Gottland. 



