174 



ECHINODERMATA PELMATOZOA 



.SUB-KINGDOM III 



angles of the stem. Arms moderately branching. Cirri generally directed 

 upwards ; those of Pentacrinus, as a rule, downwards. Recent ; Pacific Ocean. 



Extracrinus, Austin. Base composed of five rudimentary IB and five B ; 

 radials with downward prolongations from their lower ends. The five inter- 

 radial petals on the upper and lower faces of the stem-joints narrower and 

 more lanceolate than in Pentacrinus. Lias to Recent. 



(?) Balanocrinus, Ag. Stem-joints round, with serrated margins ; articular 

 faces marked by five crenulated ridges radiating from the centre. Lias to 

 Cretaceous. 



Family 9. Comatiftidae. d'Orbigny. 1 



Pedunculate and fixed in nepionic stages, later losing the stem and leading a free 

 existence. Base pseudomonocyclic; infrabasals visible only in the ciliated larva, 



afterwards becoming fused with 

 the top stem -joint. Basals, 

 which are large in the larval 

 condition, are transformed at 

 the end of the Pentacrinoid 

 stage into the so-called rosette. 

 Centrodorsal giving off numer- 

 ous cirri after detachment of 

 the stem ; its angles inter- 

 radially disposed, like the stem 

 of dicyclic Crinoids. Tegmen 

 coriaceous, naked or indurated 

 by thin calcareous plates. 



^'Z&Z'>> ' |ff 



> 



Body - cavity very shallow ; 

 arms simple, interlocking, 

 Lias to Recent. 



Wfh'l 



W 



Over 200 species are 

 represented in the present 

 seas, most of them being 

 inhabitants of shallow 

 water. 



Antedon, Freminv. 

 (Alecto, Leach ; Comatula, 

 Lam. ; Pterocoma, Ag. ; 

 Decacnemos, Brorm ; Comatu- 

 Una, d'Orb. ; Hertha, Hage- 

 now ; Solanocrinus, Gleno- 



a, Antedon (Solanocrinus) costatus, Goldf. Upper Jura (Diceras- tremiteS, Goldf.), (FigS. 235, 



Kalk) ; Kelheim, Bavaria. Dorsal aspect of crown ; centrodorsal and O rki\ TVT ^.T. 



pinnules not preserved (slightly reduced) ; b-d, A. scrobiculutus, Goldf. A a I). IVlOUtn central, anUS 



Upper Jura; Streitberg, Franconia ; b, Ventral; c, dorsal; and PP ppntriV- ppntrnrlnrcal 

 d, lateral aspect of calyx ; e, Arin-plate. ni r 1 C , C r S a 1 



button-shaped. Costals 

 two ; the upper one axillary. Arms ten or more. Lias to Recent. 



Eudiocrinus, Carp. (Ophiocrinus, Semper). Like Antedon, except that it 

 has only five arms. Represented by one Neocomian and five Recent species. 



1 Muller, J., Ueber die Gattung Comatula, etc. (Abhandl. Berlin. Akad.), 1847. 

 Ludwig, H., Beitrage zur Anatomie der Crinoideen (Zeitschr. fur wiss. Zool. XXVIII.), 1877. 

 Carpenter, P. ff., Report on the Crinoidea (Sci. Results, Chall. Exped., XI. and XXVI.), 1884-88. 

 Jaekel, 0., Entwurf einer Morphogenie und Phylogenie der Crinoideen (Sitzber. naturf. Ges.), 1894. 



