﻿ASTEROLEPID-K. 



223 



Syst. (1856), p. 63, pi. v. fig. 10.— Upper Silurian; Baltic 



Provinces 1 . 

 PUrichthys harderi, C. H. Pander, ibid. p. 63, pi. v. fig. 9.— 



Upper Silurian ; Baltic Provinces l . 

 PUrichthys striatus, C. H. Pander, ibid. p. 63, pi. v. fig. 11. — 



Upper Silurian ; Baltic Provinces. [Not Pterichthys.'] 



Genus MICROBRACHIUM, 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- 

 median. 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 : — 



M icrobrachiam dicki, R. H. Traquair, Geol. Mag. [3] vol. v. (1888), 

 p. 510, and Ann. Mag. Nat. 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 BOTHRIOLEPIS, Eichwald. 

 [Bull. Sci. St.-Petersbourg, 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. 

 Homothorax, L. Agassiz, ibid. 1845, p. 184. 

 Glyptosteus, L. Agassiz, Poiss. Foss. vol. i. 1844, p. xxxiv (name 



only). 

 Stenacanthus, J. Leidy, Proc. Acad. Nat. Sci. Philad. vol. viii. 



1857, p. 11. 



1 These species are regarded as possibly founded upon fragments of Astero- 

 Upis omata by E. yon Eichwald, Leth. Rossica, vol. i. (1860), p. 1507. 



