104 The Ottawa Naturalist. [August 



The figures suggest that the arm-facet occupies the whole upper 

 surface of the radial, but it is merely described as more than half 

 the width. Jt might be possible to distinguish facets for tube- 

 plates on the summit of x, though the phrase " its top suture on a 

 line with the top of the radials " suggests that it only supported 

 one plate. Though very different in shape from all other dorsal cups 

 ot Botryocrinus, there seems no reason to doubt Prof. Rowley's 

 ascription of his species. After all, the characters are only an in- 

 tensification of those noted in B . crassus from the same formation. 

 It should, however, be recalled that there exist other Palaeo- 

 zoic genera with the dorsal cup constructed as in Botryocrinus . The 

 Devonian representative of such genera is Cosmocrinus (Jaekel, 

 1898, Zeitschr. deutsch. geol. ges , L, Protok. p. 28). C. Holsap- 

 feli Jaekel, Poteriocrinus dilatatus Schultze, and Cyathocrinu s 

 ornatissimus Hall were referred to this genus by Dr. Jaekel, and 

 of these the first should be made genolectotype. A good figure of 

 the cup has been given only tor C. dilatatus, and this, though 

 marked with exceptionally strong axial folds, appears to have the 



characteristic Botryocrinus structure. Redescription of C. oma- 

 tissimus is much needed. At present it can only be said that, in 

 the absence ol direct evidence from the arms, there is no reason 

 for referring any other American species to Cosinocrinus. 



Cosinocrinus is a distinct side-branch of Devonian age, but 

 perhaps the American Devonian fossils here referred to Bo- 

 tryocrinus represent a transition from that typically Silurian genus 

 to the very similar Carboniferous Barycrinus. Protuberant bas- 

 als, like those ot Botryocrinus americanus, are seen in Barycrinus 

 stellatus, B. bullatus, B. subtumidus, B. mammatus, and others. 

 Perhaps indeed Botryocrinus americanus is really a Barycrinus. 

 And perhaps Botryocrinus itself should be merged in that genus. 

 Fifteen years have passed since 1 expressed my inability to dis- 

 tinguish between Botryocrinus^ Barycrinus, and Vasocrinus, and 

 since I "thought it better simply to describe the long-known 

 genus Botryocrinus as fully as possible, with the aid of new mate- 

 rial, and to leave to the American palaeontologists the task of 

 comparing it afresh with these other more particularly American 

 genera." All that American palaeontologists have done in the 

 matter since then has been to accept without discussion my refer- 

 ence of certain American species to Botryocrinus. May we not 

 hope for an independent study of this question from one of the 

 many careful workers who are now turning their attention to the 

 fossil crinoids of North America ? 



