170 BRITISH PAL.I^.OZOIC PHYLLOCARIDA. 



10. DiTHYROCARis TRicoRNis, Scoiihn; 1835. Plate XXII, fig. 4 (magnified part), 



figs. 5 a — t ; Plate XXIV, figs. 1, 5 a, b, and 6; 

 Plate XXV, figs. 9 a, h, c (?) ; Plate XXVII, 

 figs. 2 a, h, (',, 4 a — e. 



AiUiAS TRIC0ENI8, Scouler,^ 1835. Eecords of General Science (Thomson's), vol. i, 



p. 137, C<j. 2 ; and p. 141. 

 — — Bronn, 1848. Index Palajont., vol. i, p. 102. 



DrrHTROCAiiis teicohnis, Bronn, 1S48. Ibid., vol. i, p. 433. 



— — Jforris, 1854. Catal. Brit. Toss., edit. 2, p. 107. 



— — Salter and JVoodwarcI, ISljo. Chart Foss. Crust., p. 17, 



fig. 12. 



— — •/. Armstron;/, ls71. Trans. Geol. See. Glasgow, vol. 



iii. Appendix, p. 30; and Catal. W.- 

 Scotl. Fossils, 1876, p. 4r>. 



— - — H. Woodward and B. Ef!ierid//e, jun., 1873. Mem. 



G-eol. Siirv. Scot)., Espl. Sheet 23. 

 Appendix, p. 99 ; Geol. Mag., vol. s, 

 pp. 483, 480, pi. xvi, figs. 2 and 3. 



— — H. Woodioard, 1877. Catal. Brit. Foss. Crust., p. 73. 



— — Bigshij, 1S78. Thesaur. Dev.-Carb., p. 249. 



— — R. Etheridge, jun., 1S79. Quart. Journ. Geol. Soc, 



vol. xsxv, p. 466. 



— — /. Cotitts, 1884. Trans. Geol. See. Glasgow, vol. vii, 



pp. 200 and 327. 



— — E., W., and J., 1887. Rep. Brit. Assoc, for 1886, 



p. 63. 



— — Etheridge, 1888. Foss. Brit., vol. i, Pateoz., p. 238. 



— — J. Neilson, 1894. Trans. Geol. Soc. Glasgow, vol. x, 



pt. 1, p. 71. 



Specific GharaderH. — Subquadrate carapace, occurriug in both an expanded 

 (PI. Xxiv, figs. 1 and 5) and a folded state (PI. XXIV, fig. 6) ; strongly ridged, 

 both dorsally and laterally and in the cephalic region ; weak juxtadorsal ridges 

 are also present ; the two ventral margins and the dorsal line all end with a 

 strong triangular spine ; and these three, coming into a line at the hinder end of 

 the folded specimen, PI. XXIV, fig. 6, originated the name " fricornis." Surface 

 covered with a delicate reticulation, with thin irregular meshes, which thicken at 

 frequent intervals into small, short, blunt spines. 



' According to Portlock (' Report Geol. Londonderry,' 1843, p. 313), Dr. Scouler described this 

 and auDther species (A. testudineus ?) at the meeting of the British Association at Glasgow in 1840. 

 .Not mentioned in tlie Report for iliat year. 



