488 Observations on the 



in Cadaster, as all the Blastoids are possibly too nearly 

 related to admit of such differences from the true Pentre- 

 miles as are supposed to exist in Cadaster and Eleacrinus. 



PENTREMITES LINEATUS Shumard. 



A specimen of this species, with the tentacula attached, 

 shows these appendages to be long, angular, and slender, 

 composed of short joints in single (?) series ; those origi- 

 nating at the lower end of the pseudambulacral fields being 

 about as long as the length of the body from base to sum- 

 mit ; all of them directed upwards, and lying close to- 

 gether above the summit in the form of a hair pencil. 

 The condition of the specimen is not such as to show the 

 connection of the tentacula with the poral plates. 



PENTREMITES ELONGATUS Shumard. 



A crushed specimen of this species, with the tentacula 

 remaining in place, shows their arrangement to have been 

 similar to that of P. sidcatus of Roemer, as represented 

 in his " Monographic dex fossilen Crinoidenfamilie der 

 Blastoideen," and which was doubtless similar in all the flo- 

 reales. In this species they are proportionally longer than 

 they are represented in P. sulcatus, extending above the 

 summit a distance equal to one third the height of the 

 body. They appear to connect directly with the supple- 

 mentary j)oral pieces, and to abut closely against the 

 edges of the radial and interradial plates. They are di- 

 rected obliquely toward the centre of the pseudambulacral 

 field, for a short distance, and are then bent directly up- 

 ward, and lie side by side, neatly filling the field. 



The condition of the specimen under examination will 

 not admit of ascertaining their structure with accuracy, 

 but they appear to be composed of a double series of 

 short, angular plates, with parallel sutures, so arranged 

 that the sutures between the plates of one series are oppo- 



