1879.] NATURAL SCIENCES OF PHILADELPHIA. 345 



last named, that the entire genus Scaphiocrinus as formulated by 

 Hall, is identical with Graphiocrinus. Scaphiocrinus simplex, 

 and a few other species like it with a single anal plate, are un- 

 doubtedly so, but all others, and by far the majority of species 

 described under Scaphiocrinus, are generically distinct from 

 Graphiocrinus, and must be classed with Poteriocrinus. 



Closely related to Graphiocrinus are Bursacrinus, Meek & 

 Worthen, and Phialocrinus, Trautschold. We can perceive slight 

 structural differences by which the two might be distinguished 

 from the first, but it can only be a subgeneric division, and it is 

 somewhat questionable whether even this can be maintained as to 

 Phialocrinus. 



Revised Generic Diagnosis General form elongate, almost 



cylindrical. Calyx small, rather shallow, with bilateral symmetry. 

 Underbasals five, minute, rarely extending beyond the column. 

 Basals small; four at least, frequently all five of them, equal. 

 The former is the case in all species in which the anal plate is 

 disconnected from the basals, the latter when it rests directly upon 

 one of them, in which case the posterior basal is considerably 

 higher and truncate above. Radials large, their upper articulating 

 margins straight. Brachials one by five, as large or larger than 

 the radials, aud of a similar form, but with the lower margin 

 straight ; sutures gaping, articulating facet occupjing the entire 

 width of the plate. 



There are generally two arms to each brachial, or ten to the 

 individual, which remain simple throughout; but in the above men- 

 tioned species the upper side of the brachials is truncate, and the 

 Crinoid has only five arms. The arms are long and heavy, com- 

 posed of short joints with almost parallel sutures. Pinnulae long. 



A single rather small anal plate is placed half-way between the 

 radials and brachials, either resting on the posterior basal or 

 separated from it, but in either case extending above the plane of 

 the radials. Yentral sac, so far as observed, strong, composed 

 of elongate hexagonal plates. Column round or obtusely pen- 

 tagonal. 



Geological position, etc. Found so far only in the Subcarboni- 

 ferous both of Europe and America. We recognize the following 

 species: 



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