1888.] NATURAL SCIENCES OF PHILADELPHIA. 361 



sensus of opinion on this subject is much to be desired, and would 

 greatly facilitate future studies. 



From an interchange of notes with Dr. Carpenter we understand 

 that we are now in substantial agreement upon the oral question, but 

 he will shortly state his own views at length in a paper now in prepa- 

 ration. Should the views herein set forth contribute toward the es- 

 tablishment of a sound classification, we shall consider that our long 

 controversy with Dr. Carpenter, both in print and by letter, has borne 

 good fruit, and we shall waste no regrets over the fact that in some 

 points the result has proved that he was right and we were wrong. 



We give herewith a corrected diagnosis of the family Ichthyo- 

 crinidae to conform to the ventral structure as we now know it. 



Family ICHTHYOCRINIDAE. 



Test pliable. Symmetry of the calyx in-egular and usually dis- 

 turbed by anal plates. Base dicyclic. Underbasals three, unequal, 

 rarely visible beyond the column ; the smaller one directed toward 

 the right postero-lateral radial, ^ frequently anchylosed to the upper 

 stem joint. Primary radials perforate ; variable in number among 

 species and individuals from two upward ; either abutting laterally, 

 or separated by one or more ])lates. Radials and arm joints united 

 by muscles and ligaments ; line of union more or less undulating, 

 frequently with patelloid projections from the proximal margins of 

 the plates; ai'ticular surface usually occupying the Avhole distal face 

 of the first and succeeding radials. Arms uniserial, apparently 

 without pinnules. Interradials irregular in form, size and arrange- 

 ment, sometimes entirely wanting in species in which they are usually 

 present ; their lateral faces provided with deep ligamentous fossae. 

 Posterior interradius with or without anal plates ; the latter, when 

 present, frequently associated with an azygous plate. Disk, so far as 

 known, paved with irregular perisomic plates, and larger plates 

 between the rays. The center of the disk occupied by five unequal 

 orals surrounding the mouth. ^Nlouth exposed, at least in the later 

 forms. Food grooves lined by moveable covering pieces. Column 

 large, decreasing in size rapidly near the calyx. Geological Position: 

 Palaeozoic. From the Lower Silurian to the Upper Coal Measures. 



1 In the Revision, Pt. III., PL, VI, fig. 23, we represented the underbasals of Ick- 

 thyocriniis incorrectly as directed anteriorly. We have since examined numer- 

 ous specimens of various genera, and find the small underbasals located, as above 

 stated, in all of them. 



