351 Bulletin 5 



CRINOIDKA. 293 



group. The superior termination, in which the 

 ambulacrse, the rounded openings, and the central 

 angulated one, are situated, has some affinity to 

 the Family Echinidea, but the columnar support 

 shows that it cannot be arranged there. 



Having thus on its inferior portion a resem- 

 blance to the Crinoidea, and on its superior sur- 

 face a decided analogy to the Echinidea, I think 

 it may with propriety form an intermediate fa- 

 mily, under the following name and characters. 



Family BI.ASTOIDEA. 



Column composed of numerous articulating seg- 

 ments, supporting at its summit a number of plates, 

 so united as to form a calyciform body containing 

 the vicera ; arms none ; branchite arranged in am- 

 bulacrse. 



In a natural series these bodies constitute the 

 link between the Crinoidea and the Echinidea, on 

 the one hand, whilst on the other, the former is 

 unquestionably, but not more obviously, connect- 

 ed with the Stelleridica, by the unequivocal inter- 

 vention of Comatula and Marsupites. Of all the 

 genera of Crinoidea, it is to Platycrinites that 

 PenTremite seems most closely related. 



Species. 



I. P. globosa. Body subglobular ; sutures with 

 parallel impressed lines. 



[J. A. N. S., Phila., ist Ser., Vol. IV, 1825.] 



