CLASS III 



CEINOIDEA 



237 



Freminville {Ganymeda Gray; Hihemula Fleming; Fhytocrinus Bio) (Fic 

 283) ; Conipsometra, Toxometra and Iridometra A. H. Clark, etc. 



Fossil Comatulid Genera. 



The following genera are based wholly or in part upon fossil Comatulids : 

 ^/W Michelotti;^5W^/,s Schlotheim; Astrocoma Blainville; Comaty. 

 d ürbigny ; Comatuhthes 



von Schlotheim; Comaturella 

 Münster; DecacnemosBvonn ; 

 Decameros d'Orbigny, Geo- 

 coma 0. Fraas; Glenotremites 

 Goldfuss; J^er/Ä^Hagenow; 

 Microcrinus Emmons ; Ophi- 

 ■urites von Schlotheim ; Ftero- 

 coma L. Agassiz ; Solanocrinus 

 Goldfuss (Fig. 340). 



The specimens upon 

 which the type species of 

 these genera are founded are 

 rarely well enough pre- 

 served to admit of reference 

 to any one of the Eecent 

 genera, or even families, and 

 in some cases it is doubtful 

 whether they are Coma- 

 tulids at all. P. H. Car- 

 penter attempted to differ- 

 entiate the fossil types into 

 Antedons and Aäinometras ; 

 but recent discoveries have 

 shown that the endocyclic 

 and exocyclic forms are 

 by no means easy to dis- 

 tinguish, even with perfect 

 specimens, and with even 





'vt^'M 



srjki 



',,^0mik 



^ms:::!^-"^ 



W^' '<;s>^,.„ 



w ■=' 



■•»t~t 



^. 



# t 



Fig. 340. 



a, Solanocrinus costatus Goldf. Upper Jura (Diceras-Kalk); Kel- 

 heim, Bavada. Dorsal aspeet of crown ; centrodorsal and pinnules 

 not preserved (slightly reduced) ; h-d, S. scrdbicvlatus Goldf. Upper 

 the best preserved fossils '^"^''^ '■> Streitberg, Franconia ; b. Ventral ; c, dorsal ; and rf, lateral 

 . . , . aspeet of calyx ; e, Arni-plate. 



the Separation of the species 



on this basis is very unsatisfactory. A common method of procedura in 

 dealing with fossil Comatulids has been to refer them all (except those with 

 five arms, all of which belong to the genus Eudiocrinus of the Zygometridae) 

 to a Single genus, for which the name Solanocrinus is used. 



Family 5. Plicatocrinidae Zittel. 



Basal circlet funnel-shaped, quadrangidar, pentagonal or hexagonal, composed of 

 three (usitalhj), or five basals which may he solidly anchylosed. Radiais four, five, 

 six or eight (rarely seven), long and thin, hearing the post-radial series of brachials 

 on a narrow facet, which occupies only a small portion of their distal edge. Arms 

 long, undivided or branching one or more times ; the first branching usually on the 



