om>i:i< v 



CRINOIDEA ARTICULATA 



169 



stems occur notably in the Alps in great profusion, but calices 

 arc rare. 



ii'ii'ffiinhif.rinus, d'Orb. Differs from the preceding in having costals im- 

 movably united with interbrachials. Solitary species : G. dilatus, d'Orh. 

 .Jura. 



M/Ilericrinus, d'Orb. Closely allied to Apiocrinus, but articular facets of 

 ladials and brachials more strongly developed. Base occasionally with five 

 minute IB, which are coalesced with the top stem-joint (centrodorsal) ; the 

 latter extended laterally, and resting against the outer faces of the B. 

 Column more or less sharply pentagonal, with the angles interradially 

 directed. Lias to Lower Cretaceous. 



.Icrochordocrinus, Trautsch. Jura and Lower Cretaceous. 



< 'ulamocrinus, Ag. Recent; Galapagos Islands. (Cf. Literature, p. 124.) 



Family 3. Bourgueticrinidae. de Loriol. 



Dorsal cup small, pyriform, with shallow body-cavity, and composed of a centro- 

 !, five basals, five radials, and one to two costals. Tegmen (in recent foi'ms) cori- 

 acetnu, and with mouth surrounded by five orals. Arms five, thin, uniserial, and 

 bearing very long pinnules. Stem giving off numerous cirri ; composed of heavy dice- 

 box-shaped joints, both faces of which are provided with elevated transverse ridges, and 

 deep ligamentous fossae. Jura to Recent. 



Bourgueticrinus, d'Orb. (Fig. 282). Centrodorsal unusually large, as wide 

 as the calyx at its greatest width, and wider than across the basals. R 



FKJ. 282. 



Bowmutterinus dlipti- 

 Mill. White Chalk: 

 Wiltshire. , Calyx with 

 centrcxlorsal and two of 

 the stem-joints (nat. size); 

 l>, Ventral aspect (en- 

 larged); c, Stem-joints; 

 <l, Articular surface of 

 stem-joint; e, Cirrus. 



FIG. 283. 



Rhizocnnus pyriformis, Goldf. sp. Eocene ; Verona. 

 a, b, Calyx from one side (nat. size and enlarged); 

 c, !S;une from above, with three of the Jir in place ; 

 (I, Median longitudinal section of calyx (nat. size) ; 

 f, Calyx with slightly abraded outer surface, showing 

 suture lines between Ji and R ; f, Calyx with five rays, 

 seen from above (enlarged); g, k, Stem-joints (nat. size). 



truncated at the upper face, and supporting very short costals. Structure of 

 arms unknown. Column round ; its joints almost as long as wide, the upper 

 ones wider than the rest. Upper Jura to Tertiary. 



Rhizocrinus, Sars. (Conocrinus, d'Orbigny non Troost), (Fig. 283). Base 

 very large and elongate ; composed of five heavy plates which are more or 

 less fused. R typically five, but sometimes four, six, or seven ; short and 

 quadrate in form. Column slender, giving off branching cirri toward the 

 distal end ; composed of joints nearly three times longer than wide, and con- 

 stricted in the middle. Eocene, and Recent at great depths. 



