206 



Dr. F. A. Bather — The Base in the 



III. — The Base in the Camerate Monocyclic Crinoids. 



By F. A. Bather, D.Sc, F.B.S., F.G.S. 



(By permission of the Trustees of the British Museum.) 



IN "The North American Crinoidea Cam erata", 1897, Waehsnruth & 

 Springer discussed at length the various modes of partitioning 

 the base, and attempted to give a morphological, if not a physiological, 

 interpretation of the various appearances. In reviewing this part of 

 their work (Gteol. Mag., Sept. 1898, pp. 426-428) I contented 

 myself with giving a summary of their views, corrected only in so 

 far as facts of structure were concerned. This summary was 

 reprinted in the Echinoderm volume of Lankester's Treatise on 

 Zoology (1900, pp. 122, 123), although some of the theory 

 involved in it was not in accord with the phylogenetic hypotheses 

 expressed or implied in the taxonomic part of that work. Mr. Herrick 

 E. Wilson 1 has been more critical. He has brought Wachsmuth & 

 Springer's interpretations to the bar of logic, of fact, and of 

 physiological theory, and has found it necessary to replace most 

 of them by a fresh series. 



1 2 3 



7 8 9 



Figs. 1-9. — Diagrams summarising the views of Wachsmuth & Springer on the 

 structure of the Crinoid base. The posterior basal is numbered 5. The 

 region where addition is supposed to have taken place is marked + . 



Reference to Table A in Wachsmuth & Springer's monograph, or 

 to Fig. 4 in my Review (here reproduced as Eigs. 1 to 9), will show 

 an area of the base marked x or + an ^ believed by the American 

 authors to represent the portion that was added to one or other basal 

 so that it should fill out the space required. Mr. Wilson fails to 

 understand what stimulus could have initiated this hypertrophy 

 now in one place now in another; and, since the introduction of 

 such a wedge involves torsion of the rest of the basal circlet, he seeks 

 in vain for physiological processes that could bring this about or 



1 "Evolution of the basal plates in monocyclic Crinoidea Camerata " : 

 Joum. Geol., xxiv, pp. 488-510; 534-53; 666-84, pis. i-iii. August to 

 November, 1916. 



