MONOGRAPH OF THE EXISTING CRINOIDS. 123 



these points are largely morphological. Carpenter al><> contributed a paper on 

 crinoids and blastoids. 



The year 1889 saw the completion of Ilamann's work on the anatomy of the 

 crinoids; his very important memoir enters into the most minute histological 

 detail, and is concluded by a summary of the results of liis studies on the com- 

 parative morphology of the echinoderms, a discussion of echinoderm phylogeny, 

 and a critical survey of the work of previous authors. In the same year Carpenter 

 contributed a list of the crinoids of the Mergui Archipelago in which a few mor- 

 phological points are discussed; Perrier continued his monograph on the structure 

 and development of Antedon bifida, and A. moroccana; and Dr. F. A. Bather first 

 entered the field of crinoid morphology, publishing five papers dealing with fossil 

 species, but including consideration of recent forms. Bury's treatise on the com- 

 parative embryology of the echinoderms, which appeared at this time, is one of 

 the most instructive and interesting contributions to the subject ever made. 



In the following year Carpenter continued his valuable contributions, especially 

 discussing the morphological terminology; Ludwig commented adversely upon 

 Hartog's views in regard to the function of the madreporic plate and the stone 

 canal in the echinoderms; and Dr. L. Cu6not discussed in an admirable paper 

 the aboral (dorsal) nervous system, in another paper commenting adversely on 

 Hartog's theories; and Wachsmuth and Springer gave a detailed account of the 

 perisomic plates in the crinoids. 



In 1891 four papers appeared from Carpenter's pen, the most important dealing 

 primarilv with certain points in the morphology of the cystids; and Bather pub- 

 lished five articles in which more or less was said in regard to the structure of the 

 recent forms. Dr. 0. Jaekel discussed the calyx plates, and Cu6not continued 

 his interesting work on the morphology of the "soft parts." 



Dr. Oswald Seeliger's memoir on the development of Antedon adriatica was the 

 great work of 1892; in it he reviews critically the writings of Sir C. Wyville Thomson 

 on Antedon bifida, and of Bury and Barrois on Antedon mediterranea; he confirms 

 Bury's discovery of infrabasals, but finds them to be somewhat differently arranged 

 in Antedon adriatica, and four or five in number instead of usually three. 



The work of the succeeding years has been almost wholly directed toward a 

 more exact knowledge of structural details, of various physiological, developmental 

 and regenerative processes, of spermatogenesis and oogenesis, and of kindred 

 subjects, and no monographs of general scope, morphological or systematic, have 

 appeared. Cuenot, Bather, Wachsmuth and Springer, Jaekel, Perrier, Walther 

 and de Loriol have steadily continued to enrich the literature with valuable memoirs, 

 of which Wachsmuth and Springer's magnificent monograph on the American 

 Crinoidea Camerata, published by Springer after Wachsmuth's death, Bather's 

 treatise on the crinoids in Lankester's Zoology, the monographs on Uintacrinus, 

 and on the structure of Onycliocrinus, by Springer, and the various papers by 

 Cuenot, are of the most interest to the student of the recent crinoids. Of the 

 papers of less general scope special mention must be made of those on regeneration 

 by Minckert, Przibram, Riggeiibach and Morgan; on genital structures, oogenesis 

 and spermatogenesis by Danielssen, Field, W. Marshall, Cr6ty and Russo; on inter- 



