DISCOVERY OF THE DISK OF ONVCHOCRINUS 519 



iBr variable or absent . Wachsmuthicrinus 

 Arms dichotomous; Primibrachs 3. 



iBr areas wide; IBr not filling distal face of RR., 

 and connected by integument of small plates. 



IBB undivided Nipterocrinus 



II. Anal plates, when present, not united by suture with adjacent rays, 



but in armlike series, more or less separated from them by perisome. 

 C. Arms generally divergent Taxocrinidae 



a. Radianal. 



i. RA under r. post. R. 



Arms dichotomous; iBr few (T. ovalis, n.g.) Protaxocrinus 

 ii. RA obliquely to left of r. post. R. 

 Arms dichotomous; iBr few. 



Primibrachs 2 Gnorimocrinus 



Primibrachs 3 . . . {T. loveni, n. g.) Meristocrinus 



b. No radianal. 



i. Arms dichotomous; iBr variable. 



Primibrachs 2 . . . {T. affinis, n. g.) Eutaxocrinus 



Primibrachs 3 Taxocrinus 



Arms contiguous Parichthyocrinus 



ii. Arms heterotomous; iBr variable. 



20 main arm-trunks with ramules inside dichotom; 



Primibrachs 2 Synerocriniis 



10 main arm-trunks, with ramules. 

 Ramules unilateral, outside of dichotom; 



Primibrachs 3 Oligocrinus 



Ramules bilateral, branching in clusters on both 

 sides of dichotom; Primibrachs 3 or more. 



Onychocrinus 



c. No anals nor radianal. 



INTERMEDIATE FORMS OE UNCERTAIN PLACE 



Between Flexibilia and Camerata. 



Dicyclic; higher brachials incorporated in calyx by lateral union; 

 calyx pliant, plates united by loose suture; pinnulate; IBB 5; IBr 2; 

 no iBr except at anal side; anal plates in vertical succession, filling 

 area and connected by suture with adjacent brachials . . CUiocrinus 

 Between Flexibilia and Inadunata. 



Dicyclic; 5 simple arms, free from radials up; except for small, 



irregular IBr of doubtful extent; habitus of Symbathocrinus . Rhopalocriims 



Base doubtful; arms dichotomous, branching many times; rays free 

 from radials up, except for possible integument of small plates; anal 

 side doubtful . . Caleidocrinus 



