114 F. A. BATHER, CR1N0IDEA OF GOTLAND. 



This Family was founded l>v me 1 ) to include a large number of genera that had 

 mostly been grouped together with the Scaphiocrinites in one large and heterogeneous 

 assemblage called Poteriocrinidae. In this family the anal area of the dorsal cup passes 

 througb evolutionary changes that correspond in the main with those undergone by the 

 Dendrocrinidae. In accordance with those changes the family raay be split up into tive 

 or six Series not ca.pable of very exaet definition. Of these series only one has repre- 

 sentatives in the Silurian, viz., the Botryocrinites; this therefore is the onlv one that 

 concerns the student of Gotland Crinoids. 



Botryocrinites. 



Two anal plates in dorsal cup; radianal small, usually quadrangular; anal ./■ penta- 

 gonal, resting on the horizontally truncated posterior basa] and on the radianal, abutting 

 laterally on the adjoining radials, and supporting above from one to three plates of the 

 anal tube. The radianal is exceptionally absent. There is a tendency to axial folding in 

 the plates of the cup. The arms usually bear armlets, soinetimes pinnules. 



This series contains forms that link the more primitive Dendrocrinidae with the 

 Carboniferous Scytalecrinites and Graphiocrinites. Gothocrinus, here first described, is the 

 oldest raember of the series and the most ancestral in structure. Botryocrinus is at pre- 

 sent only recorded from the Silurian of Europé. Barycrinus occurs in the Lower Car- 

 boniferous of England and North America. Vasocrinus has been found in both the IV- 

 vonian and Lower Carboniferous of North America. The three latter genera are so closely 

 allied that their diagnostic characters are not very obvious; this question, however, has 

 been so fully discussed in »British Fossil Crinoids» that, in the absence of any elucidation 

 from American palaeontologists, it is unneccessary ±o reopen it here. Atelestocrinus, the 

 remaining genus included in this series, occurs in the Burlington Limestone, and is rather 

 abnormal: as it was placed among the Botryocrinites by its founders. Messrs Wachsmuth 

 and Springer, it seems advisable to leave it there, although it differs from all other genera 

 of the series in the presence of a third anal plate in the dorsal cup. 



Gothocrinus. nov. gen. 

 Diagnosis. 



T I » 1 > .">. BB 5, hexagonal, except post. B which is heptagonal. KR 5. R' separated 

 from r. post. 1» 1>\' a horizontal suture, pentagonal. Anal x rests on truncated post. B 

 and K', abuts on adjacent radials, and supports an anal tube. The two main arm-branches 

 bear armlets on either side. 



The genus mav be described as a Dendrocrinus cup with Botryocrinus arms. and 

 this mode of expression probably bits off ils place in the phylogenetic series. Only one 



') Ann. Mag. Nat. Hist., ser. 6, vol. V. p. 383; May, 1890. 



