256 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



ECHINODEEM ATA. 

 Genus Lecythiocrinus (gen. nov.). 



Etym. ATjKvdiov, a small oil flask. 



Generic formula. — Basal pieces, 3 ; subradial pieces, 5 ; first radial 

 pieces, 5 ; anal and interradial pieces, 0. 



Generic diagnosis. — The basal, subradial, and first radial pieces are 

 all well developed, none of them being minute. The dome is not known, 

 but it was very small in comparison with the size of the body. The 

 facet for the attachment of the column is small and round, but the col- 

 umn is not known. The facets for the attachment of the arms are 

 small ; the arms are not known, but they were five in number, and evi- 

 dently small and delicate. The character, shapes, and arrangement of 

 the three basal pieces are precisely as in Platycrinus, and the arrange- 

 ment of the five subradial pieces upon them is the same as that of the 

 first radials upon the basals in Platyerinus. The arrangement of the 

 first radial pieces upon the subradials is essentially the same as that of 

 Erisocrinus ; that is, they alternate regularly with each other and have 

 no anal or interradial pieces intervening. The body, which is the 

 only portion of the animal yet known, is therefore composed of thirteen 

 pieces, the arrangement of which is essentially that of five first radials, 

 all in close contact with each other, superimposed upon the calyx-struc- 

 ture of Platyerinus. Or, if it be assumed that the basal cycle of pieces 

 in the body of every true crinoid contains the elements of five pieces, 

 and that in case there are only three api)arent in tlie adult state, as in 

 Actinocrinus and many species of Platyerinus, there has been an early 

 ancylosis of two adjacent pieces in two cases, we may regard Lecythio- 

 crinus as a Cyathocrinid thus modified. I am disposed to adopt this 

 view, and I therefore refer the new genus to the Cyathoerinidw. It is 

 thought to be not improbable that if otlier species of this genus should 

 be discovered the base may be found to be composed of five separate 

 pieces instead of three, but no trace of a fourth and fifth suture can be 

 discovered in the base of the form here described. In case other exam- 

 ples should prove to possess a base composed of five pieces, the other 

 characteristics which it possesses are still sufficient to hold it as a new 

 generic form among the Crinoidea. 



Only one example of this interesting crinoid, consisting of the body 

 alone, has been discovered. It is small and delicate in structure, the 

 delicacy of the pieces composing it being similar to that of certain 

 species of Platyerinus and Diehoerinus found in the Burlington lime- 

 stone. In this respect it difiers from all the hitherto known crinoids of 

 the Upper Coal Measures, the pieces composing the bodies of which are 



