12 



Basal plates large, the two anterior each having two pits or 

 depressions on their surface, and the posterior having one; sub- 

 radials rather flat, which gives a pentangular character to the 

 lower part of the calyx, regularly pentagonal on the anterior 

 side, with shallow depressions or circular pits, which are placed 

 near the angles of the plate, and generally correspond in num- 

 ber to the angles; first radials are large, with a straight upper 

 side, and are pitted at the lower corners; intercalated plate 

 large, regularly quadrangular. All the plates seem to be anchy- 

 losed. 



About three-fifths of the calyx is preserved in the only speci- 

 men thus far found. 



PLATYCRIN'US CORPORlCULUS (N. Sp.). PI. i.'fig. 9. 



Calyx cup-shaped, column and basal plates unknown. Arms 

 large and long. Radials, five, large, hexagonal, with the two outer 

 upper margins incurved ; upper side curved outwards to receive 

 the rounding second radial, which is pentagonal, with the arms 

 branching out from the two upper faces. Arms ten, long, cannot 

 be seen to taper as far as they are preserved ; which is one-half 

 inch in the longest ; joints one-half as high as wide ; width one- 

 sixteenth of an inch, oval in section, with a projecting receptacle 

 on the lateral side of the joint to receive the pinnules ; alternat- 

 ing to the right and left with each succeeding joint. Pinnules 

 long near the arms, where they are about three-fourths as wide 

 as the height of the joint to which they are attached, and as long 

 as its width. Radials measure in their widest part one-eighth of 

 an inch. 



CALLOCYSTITES TRIPECTINATUS (N. Sp.). PI. i, fig. 10. 



Calyx oblong, sub-conical, truncate at the base, which is very 

 broad. Arms five, irregular in length, broadening at their base, 

 which apparently covered the entire summit above the third 

 series of plates ; they lie in shallow grooves into which they ex- 

 actly fit ; tentacula slender, elongate. Hydrospires, or pectinated 

 rhombs, three ; these are single, not paired, as in the allied 



