1881.] NATURAL SCIENCES OF PHILADELPHIA. 2^1 



new genus, if we had before us specimens instead of a single 

 figure. For want of material, we leave it here for the present. 



Angelin and Zittel arranged Briarocrinus under a separate 

 famil}', in which the latter includes Gulicocrinus. It is true that 

 B. injiatus deviates from all other Actinocrinidse in its interradial 

 parts, but it differs fully as much from Gulicocrinus in the same 

 characters, the latter being decidedly a Platycrinoid Briarocrinus, 

 in our opinion, leans rather toward the Ichthyocrinidse, with 

 which it agrees in the alternate arrangement of the radial plates, 

 but it has evidently not their pliant body. 



Generic Diagnosis. — Calyx cup-shaped ; symmetry pentahedral, 

 with some inequality in the sides due to irregularities in the radial 

 series. 



Basals three, usually large, two of them equal and larger than 

 the third. Primary radials 3X5, wider than high, joining 

 laterally. The third is a bifurcating plate with very obtuse 

 upper angles, supporting in almost vertical succession 3 X 10 

 secondary radials, which are half the width of the primary radials, 

 and interlock up to the second plate ; the third pair being 

 separated by a small axillary piece. The radials are generally 

 irregular in form, even those of a like order or series are differing 

 markedly among each other in height and width. In some of the 

 ra3'S, the first radials are larger by half than in others, and in 

 these the second radials are much higher and generall}' wider ; in 

 others only one side of the plate is lower, a construction pro- 

 ducing a sort of alternate arrangement of the plates, which 

 extends up to the secondary radials. The plates of this second 

 order are separated from each other, laterally, by a line of two 

 small interradial pieces, which in alternate rays, respectively, rest 

 upon the upper corners of two of the third primaries, or upon the 

 upper sloping side of the first secondary radial. 



Arms ten, supported directly upon the secondary radials ; 

 heav}^ simple, composed of single transverse round joints, with 

 parallel sutures and long pinnules. 



Posterior or anal side, so far as known, not distinct. 



Column round. 



In the absence of interradial plates between the primary radials, 

 and in the alternate arrangement of the latter, this genus differs 

 from all others of the family. 



