LOWER HELDERBERG ROCKS. 149 



FURTHER OBSERVATIONS ON THE CYSTIDE^. 



The Memoir of Von Buch "tlber CystideerC', published in 1845, giving 

 the result of his researches upon the structure and relations of these fossil 

 bodies, created a new interest in the subject of his philosophical investiga- 

 tions. Although these bodies had long been known, and several species 

 described by various authors, their zoological affinities and relations had 

 not been clearly indicated ; and no attempt had been made to separate 

 them as a group from the Crinoideae, until Wahlenberg in 1821 suggested 

 that they were animals intermediate to the Sea-urchins, Echinideae and 

 Crinoids. This writer describes, nnder the name EchinosphcBrites, three 

 species which had previously been described as Echinus by Gyllenhal and 



HiSINGER. 



M. Von Buch has advanced the opinion that these bodies constitute a 

 distinct order of Echinodermata, inferior to the Crinoids ; and this view 

 has been followed by M. de Verneuil, while Volborth, Pictet, and others 

 have maintained that they are true Crinoids, 



Prof. Edward Forbes, in his Memoir upon the Cystideae of the Silurian 

 rocks of the British islands ( Memoirs of the Geol. Survey, Vol. ii, part 

 ii, 1848), maintains the opinion first advanced by Wahlenberg regarding 

 the relations of these bodies ; presenting a very interesting and philoso- 

 phical essay upon the subject, which has been more fully noticed in the 

 second volume of the Palteontology of New- York. 



Without intending in this place any discussion of the question of the 

 relations of these fossils, it may be interesting to notice the progress of 

 our knowledge regarding them, and the additional genera and species 

 which have been published sincp the date of the Memoir of Von Buch. 



In this memoir five genera are described, viz : Hemicosmites, Crypto- 

 crinites, Caryocystites, Echinoencrinites (= Sycocystites), and Echinospherites 

 ( = Spharonites). Prof. Forbes, in his memoir cited, has added Apiocystites, 

 Pseudocrinites, Prunocystites and Agelacrinus. In the second volume of the 

 Palaeontology of New- York there have been added Callocystites, Hemi- 



