CLASS in CRINOIDEA 189 



off in clusters beneath the appendages. Anus subcentral, directly through 

 the tegmen. Devonian to Lower Carboniferous (Keokuk Gr.) ; North 

 America, Great Britain and Belgium. 



Lyriocrinus Hall {Marsupiocrinus Hall, non Blv. nee Phill.). Calyx depressed 

 hemispherical, with base rather truncate ; tegmen almost flat, composed of 

 numerous small, irregular plates. Plates of dorsal cup usually smooth or 

 granular. Arms ten, strong, unbranched, biserial. Interbrachials few, incor- 

 porating brachials to only part of the second order. Anal side usually not 

 distinct ; anus eccentric, at the end of a small tube. Fii'st interradials some- 

 times touch basals. Silurian ; North America and England. 



Thylacocrinus Q^^hlert. Eesembling Lyriocrinus, but calyx more elongate, 

 and iBr profusely developed ; anal side slightly distinct. Arms twenty or 

 more, biserial, and not branching in the free state. Devonian ; France, 

 Germany and North America. 



Anthemocrinus W. and Sp. Has one costal and few iBr. Arms biserial, 

 branching. Silurian ; Gotland. 



Bhipidocrinus Zittel {ex Beyrich MS.) (Fig. 286). Calyx similar to that of 

 Lyriocrinus. Plates highly ornamented. Rays produced into two long, heavy, 

 uniserial trunks, giving off biserial, pinnuliferous ramules alternately on either 

 side. Middle Devonian ; Eifel, Germany. 



Diamenocrinus Qi^hlert. Arms uniserial, repeatedly branching. Devonian ; 

 France and Germany. ' 



Lahuseniocrinus Tschern. ; Conclylocrinus Eichw. Devonian ; Ural. 



Ophiocrinus Salter (non Charlesworth, nee Semper nee Angelin). Devonian ; 

 South Africa. 



Family 5. Melocrinidae Zittel (emend. W. and Sp.). 



Monoeticlic. Lower brachials, with well-defined interbrachials between them, 

 forming part of dorsal cup. Badials in contact all around. Ordovician to 

 Devonian. 



Glyptocrinus Hall (Canistrocrinus W. and Sp., Pyenocrinus S. A. Miller). 

 (Fig. 287.) Basals five. Dorsal cup obconical to subglobose, ornamented 

 with radiating sti'iae passing from plate to plate • the eleva- 

 tions following the rays pronounced, and forming well-defined 

 rounded ridges, which meet imperceptibly with the free arm- 

 plates. Interbrachials very numerous, and enclosing supple- 

 mentary anals on the posterior side, which sometimes form a 

 continuous series. There are also numerous interdistichals, 

 and frequently interpalmars, which form conspicuous depres- 

 sions between the arm -plates. Tegmen low, composed of 

 minute irregular pieces ; anus eccentric. Arms uniserial, ten 

 to twenty, branching in the free state, long and slender. 

 Column round, or exceptionally pentangular. Ordovician ; ^^^ .,g^ 



rsorth America. Glyptocrinus deca- 



Schizocrinus Hall. Ordovician (Trenton Group) : New dactyius uaiLVwer 



^ r/ -J Ordovician (Ciiicin- 



York. natian) ; Cincinnati, 



Stelidiocrinus Ang. (Harmoerinus Aug.). Basals four. *^"°' 

 Form of dorsal cup as in Glyptocrinus, but interbrachials fewer and much 

 larger, and plates generally without ornamentation. Plates of the tegmen 



