ZOOLOGICAL t'llAK.UTKKS. 113 



CHAPTER VI. 



HIE ZOOLOGICAL CHARACTERS OF THE BLASTOIDEA. 



The relative rank which should be assigned to the Blastoidea among the other groups 

 of Echinoderms is still a subject of discussion; and it appears to us that Say, to 

 whom we are indebted for the name of the group, had a much more correct notion 

 of its systematic position than has been the case with many of his successors. He 

 regarded the Blastoidea as a family intermediate between the two families ol the 

 Crinoidea and the Echinoidea 1 . The word family as employed by Say, Miller, and 

 other writers during the first third of this century had a higher meaning than that 

 which is given to it by the systematists of the present day. It rather corresponds to 

 the orders or classes of modern zoology. 



It is particularly noteworthy that Say did not place his new genus Fentreviites 

 in the " Family " Crinoidea which had been established by Miller but a few years 

 before, though this might perhaps be inferred from the title of his paper. His 

 reasons for establishing an altogether new "Family " of Echinoderms for the genus 

 Pent remit es are easily understood; although subsequent writers have ignored them 

 altogether. In Miller's definition 2 of the family Crinoidea he described them as 

 having " a cup-like body containing the viscera, from whose upper rim proceed five 

 articulated arms, divided into tentaculated fingers more or less numerous." Well 

 acquainted as he was with Parkinson's ' Organic Remains of a Former World,' 

 he nowhere described the " Asterial Fossil " as one of the Crinoidea ; nor did he 

 include in this family any of the British species of Granatocrinus, Mesoblastas, or 

 Orojphocrinus from the Carboniferous Limestone of Lancashire, with one exception 3 , 

 though he cannot but have been acquainted with them. 



In the same way the phrase " arms none " occurs in Say's definition of the family 

 Blastoidea ; while in his discussion of the affinities of the Fentremite-type he said, 

 " By its columnar support it is related to the Family Crinoidea, but the total absence 

 of arms and hands excludes it from that very natural group." On the other hand, 



1 Journ. Acad. Nat. 8ci. Philad. 1825, vol. iv. pt. 2, pp. 292, 293. 



2 Op. cit. p. 7. 



3 He imagined OropTtocrmtUjpentangularia to be the cup of a Platycrinus, and described the ambulacra as 

 "the plates belonging to tbe integument that covers the abdominal cavity '" (p. b4). 



