CLASS III CRINOIDEA 209 



locking with the others, and pierced by a small anal opening. Mouth 

 subtegminal ; column composed of thin joints. Not uncommon in the 

 Middle Devonian of the Eifel and Nassau ; sparse in the Upper Devonian of 

 North America. 



Family 4. Allagecrinidae Etlieridge and Carpenter. 



Monocyclic. Calyx very small, sometimes almost microscopic. Basalsfive, radials 

 five, of irregular form and size. Some of the radials axillary and supporting two 

 arms ; others truncate and supporting hut one arm ; their articular facets provided 

 with transverse ridges and large muscle plates. Lower Carboniferous. 



Allagecrinus E. and C. B completely anchylosed in the adult, and the 

 suture lines between the orals also disappearing with age. Stem largest next 

 to the calyx, rapidly tapering downward. Carboniferous (Kinderhook to 

 Coal Measures) ; Great Britain and North America. 



Family 5. Synbathocrinidae Waclismuth and Springer. 



Monocyclic. Calyx small, howl-shaped, composed of three unequal or of five equal 

 hasals, and five nearly equal radials. Tegmen formed hy five small, astjmmetrical 

 orals ; hetween these and the posterior radials arises a long anal tube, follotuing an 

 anal, or first tube-plate', resting on the shoulders of the posterior radials. Entire 

 upper edges of the radials bevelled off so as to form straight articular facets, which 

 are furnished with well-developed transverse ridges. Arms five, simple ; column 

 round. Devonian and Carboniferous. 



Phimocrinus Schultze. The most primitive form of the family, having five 

 basals, and traces of transverse bisection of three radials as in Heterocrinus. 

 Devonian ; Europe. 



Synhathocrinus Phill. {Lageniocrinus de Koninck). B three, unequal ; B five, 

 quadrangular or pentagonal. Anal tube long, slender, resting partly upon 

 the shoulder of the right posterior radial ; it is composed of a longitudinal 

 series of strong plates with a crescentic section on the dorsal side, and small 

 plates resembling perisome on the opposite side. Arms long, uniserial, and 

 composed of comparatively thick ossicles with sharp angular edges. Devonian 

 and Carboniferous ; Great Britain and North America. 



Stylocrinus Sandb. Distinguished from Synhathocrinus mainly by the 

 character of the radial facets, which are directed obliquely downward and 

 inward, instead of upward and outward. Devonian ; Europe. 



Storting ocrinus Schultze. Devonian. 



Family 6. Cupressocrinidae d'Ovbigny. 



Dicyclic. Calyx large, basin-shaped, composed of five equal hasals and five equal 

 radials ; the basals enclosing a central pentagonal plate, which represents five anchylosed 

 infrabasals. Upper faces of radials broad, truncate, and forming an even horizontal 

 line. Costals compressed, flange-shaped. A peculiar annular structure, the so-called 

 " consolidaMng apparatus " situated on the upper interior margin of the calyx between 

 the arm-bases. Arms five, simple, uniserial and closely folded ; they are composed of 

 broad, thick plates, united hy close sutures, and are traversed hy a well-developed 



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