1886.] NATURAL SCIENCES OF PHILADELPHIA. 15T 



Parisocrinus radiatus to illustrate the genus Poteriocrinus, a spe- 

 cies without pinnules, with the arms of a Cyathocrinus, but with 

 a PoteiHocrinus arrangement of azygous plates. Under Dactylo- 

 crinus he included P. tenuis, both of Miller and Austin, T. isaco- 

 bus and P. rostratus^ Austin (pars), Monogr. Rec. and Foss. Crin. * 

 PL 9, figs. 2 b, c (non 2 a, d). Comparing Austin's P. tenuis, 

 which Sladen redescribed as Dactylocrinus loreus, with " Poferio- 

 crinus " radiatus, there appears to be considerable difference 

 between the two forms, but comparing it with P. crassus, Miller's 

 typical species, the difference is not so very great. Austin's figure 

 apparently was made from a verj' j-oung specimen, as indicated by 

 the unusuall}?^ long arm joints, and it may be a somewhat aber- 

 rant form of Scytalocrinus. Sladen 's name Dactylocrinus would 

 have priority over Scytalocrinus, had not Quenstedt in 1876 used 

 the same name for a different form. P. isacobus is, in our opinion, 

 a good Poteriocrinus. Sladen refers to Scaphiocrinus: P. latifrons, 

 Austin, which we take to be a Pachylocrinus ; and to Zeacrinus : 

 Gupressocrinus impressus {Cupressocrinus calyx ^ McCoy) ; Pote- 

 riocrinus llcCoyanus, a,nd Zeacrinus Phillipsi. We agree with 

 him as to the latter species, but we doubt if the other three are 

 sufficiently known to assert whether the calices belong to either 

 Zeacrinus, E upachy crinus or Hydreionocrinus. 



typical form, on quite as good characters as those distinguishing the latter 

 from Zeacrinus.'''' At the time of J. S. Miller the genus Poteriocrinus was 

 fully sufficient to hold every species then known, but for each species then 

 known one hundred have been discovered since. 



When we attempted to revise the Poteriocrinites we found .a confusion 

 such as existed in no other group of the PaliBocrinoidea. The subdivisions 

 that had been proposed were so indistinctly defined, and contained such 

 diverse elements, that they rather increased tlie difficulty instead of diminish- 

 ing it. As a temporary remedy we proposed our subdivisions, and expect- 

 ing they would eventually prove to be distinct genera, we applied to them 

 at once generic names. It was at the option of Prof. Worthen to accept 

 these divisions or not, but in adding some fifty or more species to the three 

 hundred already described, he surely would have aided in the identification 

 of his species, and science generally, by referring them to those groups. 

 This would have lightened the labors of others, who are now compelled to 

 look up for comparison every one of his species. Besides, if Prof. Worthen 

 had consulted the Revision, he might have avoided a number of synonyms, 

 which "cumber the nomenclature of paleontology " more seriously than 

 those few systematic names. It is somewhat curious that after refusino- 

 to accept the subgenera proposed by us and Prof. Hall, Prof. Worthen 

 repeatedly employs the specific names which had already been used by 

 previous writers in one or the other of those subgenera. 



