ON SOME PELMATOZOA FROM CHAZY LIMESTONE OF NEW YORK 1 29 



areas. The margins of the basals, radials and brachials marked 

 off by this ridge are depressed and concave. These ridges fork 

 once on the radials near their upper borders and the inner branches 

 unite to form an extremely faint medial ridge on the elevated and 

 flattened surface of the brachials. The outer ridge forks again, 

 rather more prominently, on the primaxils, the inner branches cross- 

 ing near the upper angles of this plate and thus giving the II Br 

 two prominent parallel ridges each. 



The cup plates surrounding the tegmen are very thick and heavy 

 and extend their lateral edges radially inward to the depth of 

 3 mm, a feature similar to that found inDeocrinus asper- 

 a t u s . Ambulacral grooves very narrow and not showing at all 

 on the lower plates of the first pinnules. 



Bases of arms zigzag. Lower pinnules of four or five rather 

 stout joints, each meeting its neighbor with a wide flat face for- 

 bidding an erect position of the arm bases. These bases with the 

 arms closed would project outward above 11 Br^ at an angle of 

 about 45 degrees with the axis of the cup. For the arrangement 

 of the interbrachials see cup analysis, figure 7. 



Tegmen of numerous very small pieces extending outward over 

 the lower pinnules and arm bases. 



Anal tube short and stout, about 3.5 mm high; moundlike at 

 its base with a width of about 5 mm; position very nearly central. 



Column of nearly uniform circular rings 3.3 mm in diameter 

 with a pentagonal lumen i mm in diameter; rings incised about 

 halfway in to lumen. 



Genus archaeocrinus Wachsmuth and Springer 

 Archaeocrinus ? delicatus sp. no v. 



Figure 8 



This species is described from a fragment which is remarkably 

 well preserved and free from incrustation both inside and out, 

 save that some fragments of the stem and a little deposit still 

 partly fill the basal concavity. This concavity is about 6 mm 

 across and nearly 5 mm deep. About two thirds of the depth of 

 this cup is due to five completely fused infrabasals leaving an inner 

 pentagonal opening 2 mm across. All the preserved plates are 

 remarkably thin, that is about one third of i mm in thickness, and 

 all sutures are very plainly visible save alone those of this fused 

 cup. Neither sunshine nor compound microscope shows them save 



