OHDKK III 



CRINOIDEA FISTULATA 



157 



.1A/.s//'/'"//'///s, Bather. Probably merely a variety of Cyatliocrinus, with 

 which it slum's in structure of the calyx and mode of branching. The arms, 

 however, are relatively longer, as is also the ventral tube ; column quinque- 

 partitc. Silurian; Dudley, England. 



AV/7/0/-/-/////.S-, Aug. Calyx small, cup-shaped, unsymmetrical. IB five, high, 

 si ight ly protuberant. B five, three of them hexagonal and equal ; the posterior 

 pair indented l.y the radianal. R five, very large, with excavated facets. HA 

 small, rhomlioidal, and supporting the ventral sac. Arms ten, giving off 

 a mi lets from alternate sides of each or of every second or third joint 

 throughout their entire length; in some species the armlets give off sub- 

 branches. Ventral sac in the form of a tube which coils upon itself like a 

 snail at about one-fourth the height of the arms. Anal opening situated 

 anteriorly at the base of the tube. Silurian ; Gottland. 



Wachsm. Differs from Cyathocrinus in having massive arms, 



FIG. 262. 



i n a x Kifilin a .<, 

 Mull.' Itcvoiimii; Eiti-1. !{,- 

 stored (afti-r Srhult/e). 



s, Phill. Silurian; Gott- 

 land. Crown of the natural size (after Angelin) ; 

 b, G. p^mctuosus, Aug. Tegnien ; c, Ventral and 

 lateral aspect of the arms (enlarged). 



composed of rather short, heavy, almost circular pieces, and exhibiting very 

 narrow ambulacral furrows. In some species the IE A sustains a diminutive 

 supplementary piece to the right, which is wanting in others. Ventral sac 

 composed of but few rows of heavy plates, longitudinally arranged. Column 

 stout, obtusely pentagonal, and quinquepartite ; axial canal very large. Sub- 

 Carboniferous ; North America. 



Euspirocrinus, Ang. (Fig. 219). Dorsal cup conical, composed of massive 

 plates. IB five ; B five ; R with a deep and broad articular facet, notched for 

 the passage of the axial cord. IRA large, rising above the level of the R. 

 K' idianal somewhat smaller, and supporting a plate of the ventral tube 

 which takes part in the dorsal cup. Tube cylindrical, composed of relatively 

 large plates. Tegmen formed of five interradial pieces, which support by their 

 lateral edges two rows of side pieces enclosing an irregular row of covering 

 plates. Madreporite small ; column quinquepartite. Silurian ; Gottland. 



