Talbot — New Yor~k Helderhergian Crinoids. 21 



band. Another individual (No. 5) does not show the first 

 band, and the second is broken up by weathering into five 

 comparatively broad plates and one narrow one. The next 

 specimen to attract attention (No. 6) resembles the one just 

 described only that on one side the plates succeeding the cup 

 have the appearance of a row of three short plates, instead of 

 one high one. 



It was not until these forms, seemingly so different, had 

 been most carefully compared that any conclusion concerning 

 them could be reached. The difficulty was due, mainly, to the 

 fact that in most cases the suture lines are wholly obliterated ; 

 but, witli a trace of a suture here and another there, there was 

 something on which to base an interpretation. The following 

 solution is offered : 



The genus Agassizocrinus is said to be dicyclic because 

 young specimens have infrabasals, although the latter are 

 obliterated before maturity is attained. The question has 

 arisen, Why may not the same be true of Edriocrinus ? By 

 following out this idea, these seemingly distinct forms were 

 reduced to two whose difference is simply in the development 

 of the basals, which in one group are inconspicuous and in the 

 other are enlarged to form the prominent ring or band men- 

 tioned above. 



The explanation of these varying specimens is as follows : 

 No. 2 and No. 5, instead of being monocylic, are dicyclic, the 

 infrabasals, which are the largest, being fused with the basals. 

 No. 3 shows infrabasals and basals, the latter being very promi- 

 nently developed. No. 6 has infrabasals and fractured radials, 

 but no brachials. This conclusion has been reached by com- 

 paring opposite sides of the same specimen. Though on one 

 side there seems to be a short radial followed by two short 

 brachials in each ray, the other side shows no such division ; 

 and it is evident that the apparent brachials are due to the 

 transverse breaking of the radials. This view is supported by 

 the fact that the anal plate is as high as the radials and the 

 apparent brachials combined. No. 4 shows all the plates of 

 the calyx and furnishes the clue to the others. The promi- 

 nence of the basals is hardly a specific characteristic and these 

 specimens are all left in the original species, JE. jpociUiforrais. 

 In the Yale collection, there is one example of E. sacculus 

 which gives faint indications of the presence of infrabasals, 

 though none of the specimens show any thickening of the basal 

 ring. 



In regard to classification, these forms certainly cannot 

 belong with the genus Agassizocrinus in the family Astylo- 

 crinidse, where JEdriocrinus was placed provisionally by AVachs- 



