1886.] NATURAL SCIENCES OF PHILADELPHIA. 193 



Of Gatillocrinus Wachsmuthi no descriptions were given of the 

 plates in the calyx, but the arm structure of the genus was here 

 for the first time described. Meek and Worthen, who had not 

 seen Shumard's description of Gatillocrinus, and being unac- 

 quainted with the arrangement of plates, referred their species at 

 first to Symbathocrinus, not, however, to the typical form, but to a 

 new subgenus, for which they proposed the name Nematocrinus. 

 On a republication of the species, in vol. iii, of the Geological 

 Report of Illinois, the above name was abandoned, and the species 

 placed under Catillocrinus. 



In Catillocrinus Bradleyi, Meek and Worthen undertook to 

 describe also the plates of the calyx, but without appljang to 

 them their proper terms. They simply designated them as plates 

 of a first and of a second series, except a few plates in the second 

 series which they introduced as " anals (?)." Of the five plates in 

 this series, three are easily recognized as radials, but also the two 

 others, although much smaller and very irregular in form, are 

 radials, as both are arm bearing. 



The one toward the right supports at one end an arm, at the 

 other an elongate naiTow anal plate, which abuts against the sides 

 of the proximal arm joints, and has nearly their form, being only 

 somewhat larger. Bigsby (Thesaurus Devonico-Carboniferus, p. 

 224) places Catillocrinus as a sj'nonym of Calceocrinus. 



We propose the following : 



Revised Generic Diagnosis. General form, when the arms are 

 folded, elongate-cylindrical. Calyx in form of a shalluw basin or 

 cup, concave at the bottom, uniformly truncate at the upper 

 margin. It is composed of two series of plates : the upper one 

 supporting the arms, which are very numerous. Test exceedingly 

 thin along the basals, thickening rapidly upwards. 



The basal disk is apparently undivided ; the greater part hidden 

 by the column. It is irregularly pentagonal, three of its sides 

 being nearly equal, the other two, which are adjoining, equal to 

 one-half the larger ones. The side opposite the two smaller sides 

 extends considerably bej'ond the column, while at the other side 

 the basal disk is either altogether invisible, or reduced to a very 

 narrow band. This want of regularity has been observed in all 

 specimens, and seems to be characteristic of the genus. 



Radials five, verj' irregular in form, those of the antero-lateral 

 rays much larger than the rest. The two larger plates, whose 



