44 PLATVCRINIDiE. rLATYCUINUS. 



We shall conclude our observation on the genus Platycr'mus by offering a few brief 

 remarks on some of those fossils which have been admitted into the genus on what 

 appears to be questionable evidence. Foremost among the Platycrini which we have 

 rejected, stands Miller's P. jjeH<a«_(7«Zrt/'M. The figures which he has given at page 81. 

 of his Crinoidea are compounded of various specimens ingeniously arranged in the 

 manner of a Chinese puzzle to suit the Author's ideas on the subject. 



One of the bodies figured as the Platycrinus pentangularis is in fact that of aPentremite; 

 the ambulacral rows of which Miller considered as excavations in the scapulars for the 

 attachment of arms. One figure he has represented with rays and a column. This may 

 possibly be our Dicliocrinusfits'iformis, but Miller has placed the body on the column of 

 a Poteriocrinus. 



Notwithstanding these errors the P. pentangularis was still considered as a well founded 

 species, and was said to occur in the Devonian sj^stem of rocks. Mr. PhiUips in the 

 Supplement to the Palaeozoic Fossils has represented a specimen which he refers to this 

 species, but which from its imperfect state of preservation he was unable to decide on 

 with that degree of certainty so desirable in cases of this nature. " I believe," observes 

 Mr. Phillips, " that it is really an elongate species, congeneric with Platycrinus 

 interscapularis. 



In the same work the following observation occurs — "The genus Plalycrimis has up 

 to this date never been mentioned as occuring in any other than the mountain limestone 

 strata of Britain; though on the continent of Europe it may be more widely diffused." 

 From this cjuotation it will appear that the genus Platycrinus was always considered as 

 peculiar to the mountain limestone, an opinion to which we are still inclined to adhere, 

 unless the obscure fossil from the Devonian Rocks, which Mr. Phillips has named 

 Adelocrinus HystrLv PI. \Q.fg. 42. Palaeozoic Fossils, should hereafter prove to belong 

 to that genus. 



The figures given by Continental writers, of Platycrini from foimations more ancient 

 than the mountain limestone are all representeil with divided dorso-central plates; there- 

 fore we have no hesitation in still expressing our doubts as to the correctness of retaining 

 them in tlie genus Plalycrimis. 



The impression of an oval columnar joint with a transverse raised ridge, which was 

 seen by Mr. Phillips at Pilton, cannot decide the question as to the existence of Platycrini 

 in the Devonian system of rocks, as the oval column is not exclusively characteristic of 

 that genus. The oval column occurs in the chalk, where that of the Apiocrinns elliplicus 

 is found nearly approaching in form to that of the Platycrini. The same form of column 

 may likewise bel ng to the Ile.vacrini, therefore until specimens are discovered with the 

 columns attached, we consider it tiie safest course to abstain from referring them to any 

 particular genera or species. 



