ICBlTHYOUORULITES. 
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, 
Birnbaum, near Posen, Silesia. The first of the specimens 
agrees with the spine shown in Pander’s fig. 16. 
Purchased , 186Q. 
P. 2229. Impression of ornament and some small fragments in 
matrix; Livonia. Egerton Coll. 
_ PS& ^ r' s> &y ^ 
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. a 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, tig. 14. P. / 
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 megalopteryoe by Trautschold (Zeitschr. deutsch. geol. 
Gesell. vol. xli. p. 36). - ^ 8ife/9 c/*-' 3 *) 
Form. Sr Loc. Devonian : N.W. Russia and X. Scotland . 
r T 
35019 C. Fragment from boulder at Birnbaum, near Posen, Silesia. 
Purchased. 1860. 
P. 6233. Portion of typical plate; Riga. 
Presented by Sir It. I. Murchison , K.C.B. 
P. 709. Fragment in matrix; Riga. Egerton Coll. 
P. 4598. Similar, but larger fossil; Riga. Enniskillen Coll. 
4^453. Two portions of plates gaid- to have 4regg~Obta Hiod frora - tW 
0a4th ja e B 8 Fktgstenos of lYioft . In physical characters 
one example much resembles that presented by Sir R. I. 
Murchison. Peach Coll. 
3 
