174 SMITHSONIAN INSTITUTION 



ASAPHOCRINUS nov. gen. 



(aaafyyig, indistinct; xpivov, lily) 

 Plates IV and X, figs. 10-14 



wfi (g> Q® 



Fig. 18. Asaphocrinus 



Lecanocrinidae with rays above radials separated by perisome only. Crown 

 turbinate to elongate ovoid. IBB erect, forming part of calyx wall. Radianal 

 rhombic, obliquely to lower left of right posterior radial. Anal x truncate or 

 indented above, suturally united with both adjoining rays, and followed by 

 others passing into a tube-like series. Interbrachial areas without definite 

 plates and occupied by perisome. Primibrachs two, exceptionally one. Arms 

 dichotomous, not abutting. Column of moderate size, usually enlarging at 

 calyx, terminating in a branched root. 



Genotype. Asaphocrinus bassleri Springer. 



Distribution. Silurian, Niagaran, Rochester shales to Brownsport lime- 

 stone; United States. 



This genus is proposed for the reception of certain well-marked Silurian species which 

 in spite of superficial resemblance cannot be assigned to any hitherto defined. Its affinities 

 are closest with Pycnosaccus and Gnorimocrinus. It differs from the former in the tube-like 

 series following the first anal plate ; and from the latter in the fact that this anal plate is firmly 

 united at both sides to the rays and thus incorporated into the calyx, and that the posterior 

 basal is truncate instead of excavate ; this fact precludes reference to the Taxocrinidae. The 

 large and erect inf rabasals tend strongly to associate this form with the Lecanocrinidae, which 

 in the typical species it further resembles in the large size of the radials, producing a rather 

 well-differentiated calyx. 



