OKDKK V 



CRINOIDKA AKT1CULATA 



171 



not continued over the median portion of the plate. J! with transverse 

 ridges and large muscular fossae. Stem-joints barrel-shaped. Jaekel regards 

 the centrodorsal as representing the anchylosed B, notwithstanding the 

 absi'iicv of axial canals. Upper Jura. 



PhyllocrinuSj d'Orb. Dorsal cup globose ; upper edges of 11 with narrow 

 articular facets, to either side of which are long, upright projections. 1'pjn-r 

 Jura and Lower Cretaceous, notably in the Mediterranean district. 



Family 5. Holopidae. Zittel. 



Base monooyclic ; stemless. Dorsal cup 

 aped, and formed of five fused 

 s, by which the body was either directly 

 attached, or, as was more probably the case, 

 it was suppwied by a cycle of basals 

 enclosei/ u: it bin the radials. Tegmen com- 

 posed of five large triangular orals, sur- 

 rounded by a narrow band of perisome. 

 Arms 5x2, uniserial, strongly incurving, 

 and composed of large thick plates. 



Of the forms belonging to this 

 family, Cotylederma, Quenst. (Fig. 286), is 



FIG. 286. 



a, b, Cotyledermu docens, Deslongcli. Upper Lias ; 

 May, Calvados, n, Calyx seen from above ; b, Same, 

 from below ; c, d, C. lineata, Quenst. Lias 8 ; Assel- 

 fingen ; Baden, c, Centrodorsal ; d, Circlet of fused 

 (All figures of the natural size). 



found in the Lias; Cyathidium,Steen&tr. 

 (Micropocrinus, Menegh.), in the 

 Cretaceous and Tertiary ; and 

 Holopus, d'Orb., at great depths 

 in existing seas. 



FIG. 287. 



hexagonus, Munst. Upper 

 Jura ; Streitberg, Franconia. a, Calyx with 

 radials and undivided base ; 7), c, Dorsal and 

 lateral aspects of same (slightly enlarged); 

 <'-/, First brachial, seen from the inside, 

 outside, and from below respectively. 



Family 6. 



Plicatocrinidae. 



Zittel. 



Base monocyclic, funnel- 

 shaped, quadrangular to hexa- 

 gonal, and formed of one solid 

 piece. Radials four, six, or eight 

 (rarely five or seven), short and 

 delicate. These support axillaries, 

 which give origin to two simple 

 arms composed of wedge-shaped 

 ossicles and united by muscular 

 articulation. Pinnules usually 

 composed of a single piece. Body- 

 cavity wide and deep. 



Plicatocrinus, Miinst. (Fig. 

 287). Radials comparatively 



Hyocrinti* MhelUmmx, VVyv. Thomson. Recent; Atlantic +>,: +V, iV or+iViilnr fnppf" 



Ocean. . I, Individual twice the natural size. B, Tegmen several tnm > their artlCUlar laCCt 



times enlarged ; am, Ambulacral furrows of the arms ; c, Dorsal crescent - shaped : the Outer 

 canals ; on, Anus ; m, Mouth ; o, Orals (after Wyville Thomson). . -,. n 



faces longitudinally convex. 



Pinnules undivided, except the proximal ones, which consist of three pieces ; 

 they are angular or keel-shaped along the dorsal side, and deeply furrowed 



FIG. 288. 



