ASTEROLEPIDJE. 
223 
Syst. (1856), p. 63, pi. v. fig. 10.—Upper Silurian : Baltic 
Provinces 1 . 
Pterichthys hcirderi, C. H. Pander, ibid. p. 63, pi. v. fig. 9.— 
Upper Silurian ; Baltic Provinces 1 . 
Pterichthys stricitus, C. H. Pander, ibid. p. 63, pi. v. fig. 11.— 
Upper Silurian ; Baltic Provinces. [Xot Pterichthys.'] 
Genus 3YHCROBR,ACHXXJ3YIj Traquair. 
[Geol. Mag. [3] vol. v. 1888, p. 510.] 
Form and proportions of head and trunk as in Bothriolepis, but 
pectoral appendages relatively small. The anterior median dorsal 
plate very broad ; “ its antero-lateral margin on each side first en¬ 
velops the anterior dorso-lateral, and is then overlapped by it, the 
relation of the plates to each other being thus suddenly reversed; 
behind this the postero-lateral and posterior margins of the plate 
are overlapped by the posterior dorso-lateral and the posterior dorso- 
raedian. The last-mentioned plate shows posteriorly a prominent 
angular point, projecting over the hinder opening of the carapace.’’ 
(Traquair.) 
A single small species, not represented in the Collection, is 
described thus :— 
Microbrachiwfdicki , R. H. Traquair, Geol. Mag. [3] vol. v. (1888), 
p. 510, and Ann. Mag. Xat. Hist. [6] vol. ii. (1888), 
p. 502, pi. xviii. figs. 7, 8 : Pterichthys dickii , C. W. Peach, 
Rep. Brit. Assoc. 1867 (1868), Trans. Sect. p. 72 (name 
only).—Lower Old Red Sandstone ; John-o’-Groats, Caith¬ 
ness. [Edinburgh Museum.] 
Genus BOTH RIOLiRPIS, Eichwald. 
fBull. Sc-i. St.-Pe'tersbourg, vol. vii. 1840, p. 79.] 
Syn. Pamphractus, L. Agassiz, Poiss. Foss. V. G. R. 1844, pp. 5, 20. 
Placothorax, L. Agassiz, ibid. 1845, p. 134. 
Somothorax, L. Agassiz, ibid. 1845, p. 134. 
Glyptosteus, L. Agassiz, Poiss. Foss. vol. i. 1844, p. xxxiv (name 
only). 
Stenacanthus , J. Leidy, Proc. Acad. Xat. Sci. Philad. vol. viii. 
1857, p. 11. 
1 These species are regarded as possibly founded upon fragments of Aatero- 
lepis ornata by E. von Eichwald, Leth. Rossica, toI. i. (1860), p. 1507. 
