142 BRITISH PALEOZOIC PHYLLOCARIDA. 



3. Dithyrocaris GKANDLA.TA, Woodward and Etheridge, 1873. Plate XVIII, figs. 4, 



5 a, b, 6 ; Plate XIX, figs. 5, 6 a, h ; 

 Plate XX, figs. 1 a, 6, 2 a— d, 3 a—g. 



Dithyeocaeis GRANULATE, H. Woodivard and E. Etheridge, jun., 1873. Mem. 



Geol. Surv. ScotL, Explan. Sheet 23, 

 Appendix, p. 99. 



— W. and E., 1874. Geol. Mag., dec. 2, vol. i, p. 108, 



pi. v, fig. 3 ; and Report Brit. Assoc, for 

 1873 (1874), Sections, p. 92. 



J. Armstrong, 1S76. Catal. W.-Scot. Fossils, p. 45. 



H. Woodward, 1877. Catal. Brit. Foss. Crust., p. 73. 



Bigsly, 1878. Thesaur. Dev.-Carb., p. 249. 



— J. Coutts, 1844-5. Trans. Geol. Soc. Glasgow, voL 



vii, pp. 200 and 327. 

 E., W., and J., 1887. Bep. Brit. Assoc, for 1886 



(1887), p. 64. 

 Etheridge, 188S. Foss. Brit., vol. i, Palaeoz., p. 238. 



Specific Characters. — Dithyrocaris granulata is very similar to D. glabra; but 

 it has on each valve a definite mesial (mesolateral) ridge ; and an abundant 

 granulation on the anterior and dorsal regions. These features distinguish 

 this species from D. glabra. Moreover the medio-dorsal ridge, with its side- 

 flanges, is perhaps more strong developed. It remains attached to a valve, and 

 perfect, in PL XVIII, fig. 4, and PI. XX, fig. 2 a ; and a portion of it overrides the 

 two dorsal edges of an open carapace in PI. XVIII, fig. 6, and PI. XX, fig. 1 a. 



PI. XVIII, fig. 4, and PL XX, fig. 2 a— d (magnified). Mus. Geol. Surv. 

 ScotL, F \£, No. 6. 



Size. — Length of valve, 40 mm., including the spines; breadth of valve, 

 18 mm. 



Characters. — A single left valve semi-elliptical, that is, having the shape of the 

 moiety of an ellipse that has been divided longitudinally into two halves. The 

 dorsal edge is straight ; the ventral has a symmetrical elliptical curve. The ends 

 differ ; the anterior, defined by the rising and narrowing curve of the ventral 

 border, bears a short antero-dorsal process, above which (to the right or left in 

 the figures) the dorsal border begins with an ogee curvature. The posterior end 

 is more broadly curved, but turned in suddenly to meet the junction-line of the 

 valves, so that the dorsal border ends in a medial recess. The hinder border, 

 moreover, is marked by a strong, postero-ventral, triangular, flat, sharp spine, 



