PALAEOZOIC ECHINODERMATA. 109 



of the P. pileatus, Gold. (P. antheliontes, Aust.), which it much 

 resembles, but from which it is easily distinguished by the above 

 characters. 



{Col. University of Cambridge.) 



Actinocrinus [Amphoracrinus ?) olla (M'Coy). 



Sp. Char. Inversely pyriform, very gibbous ; arm-bases small, 

 not very prominent ; cup below the arms hemispherical, visce- 

 ral portion above very wide, elevated, cylindrical ; all the plates 

 above and below flattened ; pelvis small, flattened, pentagonal, 

 supporting on four of its sides four large hexagonal first-costal 

 plates, about one-third wider than long, and on the fifth side 

 one pentagonal plate; the five regular second costals are scarcely 

 one-third wider than long, smaller than the first-costals and 

 hexagonal, with the two upper lateral sides so short as some- 

 times to make the plates seem quadrangular ; intercostals hex- 

 agonal, longer than the first-costals ; pectoral plates rather 

 large, flat, polygonal ; scapulcB pentagonal (or occasionally with 

 the upper lateral angles truncated so as to be slightly hepta- 

 gonal), one-third shorter than the first-costals ; interscapulars 

 heptagonal or octagonal, as long as the intercostals ; the sur- 

 face of all the plates marked with minute vermicular wrinkles. 

 Diameter of cup 1 inch 9 lines. 



The sculpturing resembles that of the A. (Amphoracrinus) am- 

 phora, from which the species is distinguished by its round inflated 

 pot-like figure, small arm -bases, proportionate length of the 

 costals, &c. 



Very common in the Derbyshire carboniferous limestone in 

 company with the Poteriocrinus granulosus. 



{Col. University of Cambridge.) 



Actinocrinus {Amphoracrinus) Atlas (M^Coy). 



Sp. Char. General figure of body elongate-oval, diameter between 

 the arms little more than half the height of the body ; pelvis 

 pentagonal, of three thick flattened joints ; first-costals small, 

 one pentagonal and five wider heptagonal, the latter nearly twice 

 as wide as long ; second costals as long as the first, but only 

 one-third wider than long, hexagonal or sometimes quadrate 

 (according as the upper lateral angles are entire or slightly 

 truncated) ; scapulce short, pentagonal, as wide as the second 

 costals ; intercostals hexagonal, exceeding the first-costals in 

 length ; arm-bases prominent, and over each is an elongate 

 conical ivhevcYe, ; pectoral plates rather large, convex and irre- 

 gularly polygonal ; vertex covered by a very large hemisphe- 

 rical plate, surrounded by six slightly smaller polygonal ones 



