IpO SMITHSONIAN INSTITUTION 



MESPILOCRINUS De Koninck and Le Hon 

 Plate V, figs. 1-24I1 



Mespilocrinus De Koninck and Le Hon, Recherch. Crin. Carb. Belgique, 1854, p. 111 and text fig. — 

 Pictet, Traite Palaeontologie, IV, 1857, p. 320. — Hall, Supplement Geol. Iowa, I, pt. 2, i860, 

 p. 69. — Bronn, Klassen u. Ord. Thier-Reichs, II, i860, p. 231. — Schultze, Mon. Echinodermen 

 Eifler Kallces. 1867, p. 152, sep. (1866), p. 40. — Beyrich, Montasber. Akad. Wiss., Berlin, Feb., 

 1871, p. 46; Transl., Ann. and Mag. Nat. Hist., (4) VII, p. 403.— Von Zittel, Handbuch Palaeon- 

 tology, I, 1879, p. 35s ; Grundziige Palaeontologie, 1895, p. 138. — Wacbsmuth and Springer, 

 Revision Palaeocrinoidea, pt. 1, 1879, p. 41; ibid., pt. 3, 1886, p. 144; Proc. Acad. Nat. Sci., Phila- 

 delphia, 1890, p. 388. — Miller and Gurley, Bull. 9, Illinois St. Mus., 1896, p. 39. — Zittel-Eastman, 

 Text-book Palaeontology, I, 1896, p. 164; 2d Ed. 1913, p. 203. — Bather, Treatise on Zoology 

 (Lankester), pt. 3, 1900, p. 188. — Springer, Amer. Geologist, XXX, 1902, p. 94; Jour. Geology, XIV, 

 1906, p. 517. — Young Poteriocrinus, Phillips, Geol. Yorkshire, II, 1836, p. 205. 



6q5 



Fig. 20. Mcspilocrinus 



Lecanocriniclae with rays in contact except at anal side. Crown globose to 

 ovoid. Infrabasals usually erect, extending beyond the column; exceptionally 

 five in number. No radianal. Anal plates one or more, filling the interradius ; 

 no interbrachials in other areas. Primibrachs two. Rays usually abutting but 

 not interlocking; often asymmetrical, with dextrorse twist. Arms dichotomous. 

 Column not enlarging proximally ; composed near the calyx of short columnals, 

 becoming longer below ; these vary in form from cylindrical with straight sides 

 and no depression at the sutures, or simply convex or barrel-shaped with 

 indented sutures, to greatly elongate, doubly conical, spindle-shaped segments, 

 widest in the middle. The column is frequently curved so that the calyx hangs 

 downward. 



Genotype. Mespilocrinus forbesianus De Koninck and Le Hon. 



Distribution. Lower part of Lower Carboniferous; Belgium, England and 



the United States. 



Mespilocrinus is a Lecanocrinus minus the radianal — its legitimate successor in struc- 

 ture as well as time. Along with this modification there is a tendency to specialization, 



