374 PROCEEDINGS OF THE ACADEMY OF [1881. 



think the so-called fourth radial is an arm-bearing secondary 

 radial, which is given off in a similar manner as is the plate which 

 supports the first arm in Steganocrinus scitlptus (PI. 18, fig. 3); 

 this explains sufficiently the form of the third radials, which are 

 here truncate above instead of axillary as usually. The arms are 

 unknown, but we judge from the enormous size of the so-called 

 arm openings, which form large breaks, that the bodj' in this genus 

 was extended into lateral appendages, and gave off numerous arms. 



Generic Diagnosis. — Body oblong, contracted between the arm 

 bases, except the posterior side, which toward the dome bulges 

 considerably, thereb}- producing some irregularity in the general 

 form. Calyx, cup- or urn-shaped, beautifully ornamented with 

 radiating strife. 



Underbasals five, forming a pentagon, the plates of equal size, 

 quadrangular, the sides of the outer angles shorter. Basals five, 

 large, sometimes fully as large as the first radials, four of them 

 equal and angular above, the posterior one considerably higher 

 and its upper side truncate. Primary radials 3(?) X 5, wider 

 than high, all three hexagonal and with truncate upper side, 

 decreasing in size upward ; the third not more than one-fourth 

 the size of the first. Higher orders of radials unknown, but 

 probabh' formed into free raj-s which give off arms laterally. 



The interradial plates extend uninterruptedly into the vault, 

 those of the calyx and vault being undistinguishable ; indeed, in 

 this genus it almost appears as if the interradial pieces of the 

 calyx extend up to the proximal vault pieces. The first inter- 

 radial rests slightly between the upper sloping sides of the first 

 and between the second radials, with a number of series above, 

 composed of two or three plates each. The first anal plate rests 

 directly upon the posterior basal, which is of such great height 

 that the upper side of the anal is horizontally in line with the top 

 of the first interradial. There are three plates in the second and 

 all succeeding series, arranged longitudinally, forming three 

 rows, of which the plates of the median one are wider and marked 

 by an elevated ridge. 



Form of the vault unsymmetrical, bulging at the posterior 

 side, with a subcentral anal tube ; plates rather large and nodose, 

 the radial ones decreasing in size toward the arms. 



The apical dome plates, although not distinguished by size, are 

 readily recognized by their position. Length of anal tube unknown. 



