204 
AN TI ABC HA, 
with tubercles ; [tail unknown]. Lateral sensory canals upon the 
upper aspect of the head united by an anterior transverse commis¬ 
sure crossing the premedian plate, and by a posterior one directly 
crossing the median occipital; anterior median dorsal plate over¬ 
lapping both the anterior and posterior dorso-laterals. Pectoral 
appendages shorter than the armoured trunk, segmented into a 
distal and proximal portion. 
This genus is only known from isolated dermal plates so similar 
in form to those of Ptericlithys as to have induced C. H. Pander 1 to 
regard the last-mentioned name as a synonym. The only un¬ 
doubted distinguishing feature, according to R. H. Traquair 2 , is the 
mode of overlapping of the anterior median dorsal plate. The tail, 
however, is still unknown. 
Asterolepis ornata ? Eichwald. 
1840. Astrolepis, E. Eic-hwald, Bull. Sci. St.-Petersbourg, vol. vii. p. 79. 
1840. Asterolepis ornata, E. Eichwald, Neues Jalirb. p. 425. 
1844. Asterolepis ornatus, E. von Eichwald, Bull. Soc. Imp. Nat. 
Moscou, vol. xvii. p. 829. 
1845. Asterolepis ornata , L. Agassiz, Poiss. Foss. Y. G. R. p. 93, pi. B. 
fig. 4 ; pi. xxx. figs. 2-9 (? in part). 
(P) 1845. Asterolepis apicalis, L. Agassiz, op.cit. p. 148, pi. xxxi. a. 
fig. 31. 
1857. Asterolepis, C. H. Pander, Placoderm. devon. Syst. p. 44, pi. v. 
figs. 10, 11, pi. vi. figs. 1-4, pi. vii. figs. 1, 8, pi. viii. fig. 4, pi. B. 
figs. 6, 7, 10, 13, 14. 
1800. Asterolepis ornata, E. von Eichwald, Leth. Rossica, vol. i. p. 1508 
pi. lvi. fig. 1. 
Type. Detached dermal plates ; Lmiversity of St. Petersburg. 
The type species. Anterior median dorsal plate not carinated 
longitudinally, its anterior extremity almost as broad as the poste¬ 
rior. Unworn superficial tubercles with prominently stellate bases, 
irregularly arranged, and sometimes fused together; outer margin 
of pectoral appendages acute and coarsely denticulated. 
Form . Loc. Devonian : Baltic Provinces and Government of 
Novgorod. Russia. 
The following specimens are detached plates from the neighbour ' 
hnod-u>f-T4orpat, and, unless otherwise stated, were obtained by 
purchase, 1868 :— 
41090 a. Premedian. 
1 Die Placodermen des devonischen Systems (1857), p. 44. 
2 Geol. Mag. [3] vol. v. (1888), p. 508 ; also Ann. Mag. Nat. Hist. [6j vol. ii. 
(1888), p. 402. 
