1898-1902. No 33. 



UPPER DEVONIAN FISH REMAINS. 



35 



The.se nssiiiH(iti(iiis of PaiXoek are mainly of historic interest as far 

 as we are concerned. After TiiAuii.viu'^ investigations, wliicli iiave been 

 earned fmilier l>y my own jiroofs of tlie structure of the skeleton, it has 

 Lieen consulei-etl certain that Psainmosteus. Drepanaspis and Pteraspis 

 ai-e nearly related forms. Drrpanaspis, the dermal skeleton of which is 

 kno\vn in most details, should therefore provide us in the main witli a 

 re|iresenlahoii ol the a|>|(eaiance of Fminmosteus as well. 



In this connection, linwever, it is of great interest to note that the 

 PsainiHosfeii.s remains in Ihe East I'rovinces of Russia according to 



Fig. 8. Sli(--k-l[ showing llie structure o( t\]f i\eriaii\ skeleton it( Psauintosteus niaean- 



<h'i)ins Ai., We see the dermal slieloton eat throiigli in two directions At tlic 



top, tlie llatli'ned dentirle.s with their line, narrow pulp cavities and line dentine 



luhules; below these the vascnlar canal system. 



Pandlu's theory lieloiig to one species, which would in that case receixe 

 the name Ps. mueandrbius Ag. 



A. SMrrii-\Voor)WAr,D in hi^ catalogue ^ names Agassiz's species 

 without gn'ing his rea^ons for so doing. 



In realitv a fresh investigation is required, — particularly of Ihe 

 microscopic structure — in order In decide this question. 



Personallv I have onlv had a few Psainmosteus remains from Ihe 

 Bailie Provinces for comparison, viz. a spine shaped element from the 



1 Catalogue of the Fossil Fi.shes in the British Museum, 11, 1891, page 126. 



