226 



ECHINODERMATA— PELMATOZOA 



PHYLUM IV 



Dittmar iion Billings) (Figs. 329-331). No anal x noi^ tube-plate visible 

 Calyx low, with base more or less concave. 

 Infrabasals five, minute, concealed in the basal 

 concavity, sometimes reduced to three, or atro- 

 phied. Arms usually ten, exceptionally twenty; 

 uniserial at their lower ends, but soon becoming 

 biserial ; separate axial canal in radials, extend- 

 ing into the arms. Tegmen not definitely 

 known. Stem round, apparently without cirri. 

 Abundant in the Trias, especially in the 

 Muschelkalk of Germany. The stem fragments 

 of E. liliiformis frequently form beds of marine 

 limestone (Trochitenkalk). p^^ g^r, 



„, . „ 1 • J- 1 1 ii • -4- DiaL'iam showing course of axial canals 



This genus was formerly associated by the majority in the calyx and arms of 7?»cr wins. Canals 



of European authors with the Recent Crinoids under the represented by dotted lines when pene- 



Articulata. It was shown by Wachsmuth and Sijringer tratinj; the interior of the plates, and by 



that its rehxtions are clearly with the later Paleozoic ':::^l^X^^t,^m^'' '""" 

 Inadunata, and its position as such is recognised by 



most recent writers. The type species, E. liliiformis, by reason of its striking appearance 



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hr-i 



Fig. 330. 



Encrinus Uliiformin 

 Miller. Mnschelkalk ; 

 Brunswick. 



Portions of the calyx and arms of Encrinus. a, Interior 

 of calyx ; a', Exterior of same ; b, Basal, upper surface ; 

 r, Radial, inner surface ; j3. One of the uniserial, and (3*, bi- 

 serial arm-i^lates ; both of them traversed by duiilicate 

 dorsal canals ; p, Pinnule ossicle (enlarged) ; hi; First 

 brachial, under surface ; ftfi 2^ First and second brachials 

 joined together ; inside, seen from below ; hr^, First brachial, 

 upper surface, showing line of syzygial suture ; hr'^, Second 

 brachial (axillary), showing articular facets. 



and beautiful preservation, early attracted the attention of observers. The generic name 

 was first applied in 1760 ; and the form is the best known of all fossil Crinoids. 



Order 4. ARTICULATA. J. S. Miller (emend. J. Miiller). 



Tegmen coriaceous, studded with minute calcareous particles, which may he quite 

 invisible externally, or may he enlarged into well-defined plates that rarely form a 

 complete investment. Mouth and food grooves exposed, hut often bordered with one 

 or two rows of side and covering plates capable of being closed down over them. 

 Orals present in the young, often also in the adult. Plates of the dorsal cup, except 



