DESCRIPTIONS OF THE SPECIES. 297 



Family ASTROClilM U.K. T. & T. Austin, 1843 (emend. E. & C, 188C). 

 (i.) Basals unsym metrical. Azygos radial 

 small and without definite limbs ; its 

 ambulacrum short, wide, and hori- 

 zontal. 



Calyx ovoid Eleutherocnn us, Shumard and Yandell. 



Calyx low and stellate Astrocrinus, T. & T. Austin. 



(ii.) Basals symmetrical, odd ambulacrum 



linear Pentephyllum, Haughton. 



"We have divided the family into two groups, because even the little we 

 know of Pentephyllum shows that it is a much less abnormal form than either 

 Eleutherocrinus or Astrocrinus, and we think it more than probable that it will 

 eventually have to be made the type of a new family of irregular Blastoids. Under 

 these circumstances, the characters appended to Group (i.) in the above scheme will 

 become the distinctive characters of the family Astrocrinidae. 



The National Collection contains no example of Eleutherocrinus, and we are there- 

 fore precluded from describing it. We regret this the less, however, as an excellent 

 diagnosis of it has been already given by Shumard and Yandell ; and by the kindness 

 of Mr. "Wachsmuth we have been enabled to give some figures of the genus on 

 Plate XIX. for comparison with those of Astrocrinus on the next Plate. 



Genus ASTROCRINUS, T. & T. Austin, 1842 {emend. E. & C, 1886). 



Astrocrinites, T. & T. Austin (MS.) 1 , Ann. & Mag. Nat. Hist. 1842, vol. x. p. 112 ; Ibid. 



1843, vol. xi. p. 205. 

 Zygocrinus, Bronn, Index Pal. Nomen. 1848, p. 1381. 



Zygocrinus, Roemer, Archiv f. Naturgesch. 1851, Jahrg. xvii. Bd. i. p. 392. 

 Zygocrinus, De Koninck & Le Hon, Mem. Acad. Roy. Belgique, 1854, torn, xxviii. Mem. 3, 



p. 189. 

 Astrocrinus, Morris, Cat. Brit. Foss. 2nd edit. 1854, p. 72. 

 Zygocrinus, Pictet, Traite de Pal. Strat. 1857, torn. iv. p. 295. 

 Astrocrinites, Etlieridge, Jr., Quart. Journ. Geol. Soc. 1876, vol. xxxii. p. 103. 

 Astrocrinus, E. & C, Ann. & Mag. Nat. Hist. 1883, vol. xi. p. 234. 



Gen. Char. Calyx free, obtusely tetralobate, with one of the ambulacra peculiarly 

 modified ; summit truncate and flattened ; base resembling it, or sometimes a little 

 pointed. Basal plates unsymmetrical and not united to form a cup, the azygos one 

 being more or less triangular, and dorsocentral in position ; the other two alike, and 



1 Non Asterocrinitts, iliinster, Beitriige zur Petrefactenkunde, 1S43, Heft ], p. 33; nee Asterocrinus, 

 Lyon, D. D. Owen's 3rd Report Geol. Survey Kentucky, 1S57, p. 47-. 



2q 



