364 PROCEEDINGS OF THE ACADEMY OF [1888. 



CROTALOCRINUS : ITS STRUCTURE AND ZOOLOGICAL POSITION. 

 BY CHARLES WACHSMUTH AND FRANK SPRINGER. 



The tyi^e of Crinoids that has been described under the name 

 Crotalocrintis, is one of the most extraordinary yet brought to light 

 from palaeozoic rocks. Its net-formed radial appendages, so widely 

 different from those of any other known Echinoderm, and resem- 

 bling rather the fronds of a Bryozoan than the arms of a Crinoid, 

 have long made it a puzzle to naturalists, and the efforts of all 

 writers up to the jDreseut time — ourselves included — have contribu- 

 ted but little toward any satisfactory determination of its systematic 

 relations. Though so highly differentiated in its structure, the 

 genus is confined to the upper Silurian, so far as known. It ha& 

 been found in the island of Gothland, Sweden, where it was first 

 noticed by Hisinger in 1828, and afterwards described by him as a 

 Cyathoerinus in 1837. It was also found at Dudley, England by 

 Parkinson in 1808, who called it the Turhan or Shropshire Encri- 

 iiite ; and it was redescribed by J. S. Miller in 1821, as Cyathoerinus 

 rugosus. No trace of it has ever been discovered at any other locality. 

 Good specimens are rare and diflScult to obtain, so thai the facili- 

 ties for its study, outside of the countries where it occurs, have 

 hitherto been practically nil. 



The arm structure was not understood until 1854, when Johannes- 

 Miiller figured and described under the name xinthocvinus Loveni 

 the principal Swedish species, although Austin had established the 

 genus Crotalocrinus in 1843, for the English form, without figure 

 and with a very meagre description. Angelin's elaborate work on 

 the Swedish Crinoids in 1878, contained numerous beautiful figures 

 of apparently perfect specimens, and seemed to give the most ample 

 illustrations of every part elucidating the structure of this curious 

 fossil. Upon these descriptions and figures, and without any oppor- 

 tunity to study even a single specimen, we prepared our descrij)tion 

 of the genus, and discussions relating to it, as they ajipeared in Part 

 III of our Revision of the Paljeocrinoidea. 



Not long after the publication of this work, w^e found reason to 

 believe that our interpretation of the structure and affinities of 

 Crotalocrinus was erroneous, and that much of what we had written 

 on the sul)ject was altogether worthless. During a visit of one of 

 us to Europe last winter, he had an opportunity of examining the 



