﻿ICHTHYODORULITES. 127 



on the opposite side ; but this feature may possibly be due 

 in part to accidental abrasion towards the proximal end. 

 The convex border of the spine exhibits evidence of wear 

 during life, the ornament having been destroyed. 



Purchased, 1884. 



35019, a, b. Three fragmentary, short, blunt spines, of a type 

 different from the above, but closely resembling the latter 

 in ornamentation : from a boulder of Old Red Sandstone, 

 Birnbauin, near Posen, Silesia. The first of the specimens 

 agrees with the spine shown in Pander's fig. 16. 



Purchased, 1860. 



P. 2229. Impression of ornament and some small fragments in 

 matrix; Livonia. Egerton Coll. 



Psammosteus arenatus, Agassiz. 



1844. Placosteus arcuatus, L. Agassiz, Poiss. Foss. vol. i. p. xxxiii 

 (name only). 



1845. Psammosteus arenatus, L. Agassiz, Poiss. Foss. V. G. R. p. 105, 

 pi. xxxi. figs. 7-10. 



1857. " Ichthyodorulith," C. H. Pander, Placoderm. devon. Syst. p. 102, 

 pi. vii. fig. 22. 



1858. Psammosteus arenatus, G. Kade, Programm k. Realschule zu 

 Meseritz, p. 10, fig. 14. 



Type. Unknown. 



By Eichwald (Leth. Rossica, vol. i. p. 1510) the plates thus 

 described are doubtfully associated with the so-called Asterolepis 

 depressus ; while the triangular spine figured by Pander is ascribed 

 to Coccosteus megalo_pteryx by Trautschold (Zeitschr. deutsch. geol. 

 Gesell. vol. xli. p. 36). 



Form, St Loc. Devonian : IST.W. Russia and N. Scotland. 



35019 C. Fragment from boulder at Birnbaum, near Posen, Silesia. 



Purchased, 1860. 



P. 6233. Portion of typical plate ; Riga. 



Presented by Sir JR. I. Murchison, K.C.B. 



P. 709. Fragment in matrix ; Riga. Egerton Coll. 



P. 4598. Similar, but larger fossil ; Riga. EnnisJcillen Coll. 



42453. Two portions of plates said to have been obtained from the 

 Caithness Flagstones of Wick. In physical characters 

 one example much resembles that presented by Sir R. I. 

 Murchison. Peach Coll. 



