ISOTELUS, ACROLICHAS, CALYMENE, AND ENCRINURUS , 81 
ADDITIONAL NOTES ON BRASSFIELD ECHINODERMATA 
Since the publication of the article on the echinodermata of 
the Brassfield Formation, in the earlier part of this volume, 
Mr. Frank Springer, the eminent American authority on Cri- 
noidea, has kindly offered the following notes on several of the 
specimens there figured. 
The broad, flat calyx, represented by figures 2 A, B, C, and D on plate Vl, 
belongs to the Rhodocrinidae, and may be similar to the form described by 
Weller, from the Racine of the Chicago area, as Archaeocrinus depressus. 
Hitherto we have supposed- this genus to be purely Trenton and Chazyan, but 
the Racine and Brassfield forms appear to be close to it. 
The specimen retaining both calyx and arms, obtained at the Centerville 
quarry, and forming figure 3 on plate III, is of the type PaielUocrinus Angelin, 
one of the rare Gotland forms, but the preservation of the Centerville specimen 
is tantalizing, and one does not feel sure of the structure. 
The fragments of calyx and arms forming figures 4 A, B, on plate III, also 
found at the Centerville quarry, apparently belong to the Flexihilia, and very 
probably is Pycnosaccus , as far as can be determined in the absence of an 
entire calyx. 
The problematical specimen described on page 28 as Stereoaster squamosus 
forms the genotype of Stereoaster, the latter being a new generic term, a fact 
not indicated in the text at the time of its original publication. 
