% 
128 
ICHTHYODORULITES. 
\o is 
Psammos^s paradoxus, Agassiz. 
1844. Psammolepis paradoxus, L. Agassiz, Poiss. Foss. vol. i. p. xxxiv. 
(name only). 
1845. Psammosteus paradoxus , L. Agassiz, Poiss. Foss. V. G. R. 
p. 104, pi. B. figs. 5, 6, pi. xxvii. figs. 2-4. p nu . , 
£ > - /V- "■ trr9. • s X/-U .1*/. /0. %£p 
Type. Unknown. 7 - A. f/y f-7ft ; n 
Form. 6f Loe. Devonian : F.W. Russia. 
P$a Stefas 
pa*+*C*££*. 
If*, C <Xo 4^33 
iVt,n.U-fy 
/A-e,iA- . 
P. 4491. Much abraded plate, with surface ornament partly re- 
^.9 : • moved; River Ssjass. Purchased, 1884. 
if /*' 
~)G 
l 
/ 
P. 5959. Well-preserved portion of plate, 0-005 in thickness; 
Juchora, River Ssjass. In addition to a general fine 
rugosity, the inner aspect exhibits a few short, srpall, 
irregularly disposed grooves, with raised lateral borders 
(pf. fig. of “ Asterolepis asmussi ” in Pander’s Placoderm. 
devon. Syst. pi. vii, fig. 32). Purchased, 1889. 
Other plates have also been assigned to Psammosteus under the 
following names :— 
Psammosteus grcinulatus, F. M‘Coy, Ann. Mag. Rat. Hist. [2] 
vol. ii. (1848), p. 7.—Lower Carboniferous ; Kesh, Co. Fer- 
)P\cl^S ' managh. [Dublin Museum.] 
Psammosteus undulatus, L. Agassiz, Poiss. Foss. Y. G. R. (1845), 
7 j\ , P- 106, pi. xxxi. figs. 11, 12/: Plcicosteus undulatus , 
' L. Agassiz, Poiss. Foss. vol. i. (1844), p. xxxiii (name 
i. % onl y)-—Devonian ; N.W. Russia. 
; a^^A^WMmosteus vermicularis, F. M‘Coy, tom. cit. p. 7.—Lower Car- 
l boniferous; Fallaghloon, Maghera. [Dublin Museum.] 
^2■']*& ' fv Tlie P late described as follows also exhibits some external 
resemblance to Psammosteus , but its histological structure is un¬ 
known :— 
if *-A. 
: © 
* 
Lophosteus superbus, C. H. Pander, Foss. Fische Silur. Syst. 
'y ny) (1856), p. 62, pi. vi. fig. 23.—-tipper Silurian Ohhesaar, 
Island of Oesel. A &Z t 
*, /f 54 %. & , ^ &*-***> 
In general external aspect the spines from the American Corni- 
- ferous Limestone named Acanthaspis (J. S. dewberry, Rep. Geol. 
Surv. Ohio, vol. ii. pt. ii. 1875, p. 36) and Acantholepis (J. S. Hew- 
berry, ibid. p. 38) are very suggestive of the triangular ichthyodo- 
rulites assigned above to Psammosteus : their histological structure, 
*2.?d , 
