1890.] NATURAL SCIENCES OF PIirLADELPIIIA. -389 



is rounded, composed of irregular pieces, pierced by a small aperture, 

 which opens out somewhat anteriorly and evidently served as anus. 

 The structure indicates clearly, that this tube is quite different from 

 the solid conical protuberance which occurs in the recent genus. 

 Tlmuviatocrinus, with which it has been compared. The latter we 

 regard as a most remarkable instance of atavism. The projection 

 consists of a vertical row of fourteen or more j)lates rising to the 

 height of the anal tube, placed in front of it. It recalls the ventral 

 sac of the Fistulata, among which also apparently the anus some- 

 times is placed in front of the tube. In Goeliocrimis with a balloon- 

 shaped sac, which is sometimes found detached so it can be examined 

 from all sides, we have searched in vain for an opening, and we have 

 no doubt that in this genus, and probably in many others, the anus 

 was located near the mouth as in Thaumatocrinus. 



No other genus among the Crinoids has so wide a range, and un- 

 dergoes so few modifications as Ichthyocrinns. We find it already 

 in the Lower Silurian, and it lived through to the time of the Upper 

 Coal Measures, and was quite probably the ancestor of the Apiocri- 

 nidae, Pentacrinidae and Comatulidae of our present seas. 



There are in the paper of Mr. Bather several inaccurate references 

 to our previous writings, to some of which we are compelled to di- 

 rect attention, as much as we regret it, else it would appear that we 

 had actually made such inconsistent and irrational statements. 



On p. 322, he says that in our paper on Hybocrinus, Hoplocrinus 

 and Baerocrinus, we considered the " Azygos plate to be an inde- 

 pendent morphological element of the dorsal cup, not a modified 

 radial," and on p. 323, he alludes to our " previous view that the 

 Azygos plate was a primitive fundamental element of the dorsal 

 cup." We know of no passage in that paper from which Bather 

 would be entitled to draw any such inferences. As he lays so much 

 stress upon this in his criticism, he should have quoted the exact 

 language, and give the page where it occurs. 



On p. 324, in summing up the position which we held in 1886, he 

 makes the following astonishing statement: 



"(1.) Azygos plate (Az) a primitive element of the dorsal cup. 



(2.) Anal (x) and right posterior radial derived from Azj^gos 

 plate. 



(3.) Anal of Antedon not homologous with any plate of the 

 Fistulata, but an embryonic interradial." 



