40 BRITISH PALAEOZOIC PHYLLOCARIDA. 



C. stygia was rather larger than G. papilio ; its telson was larger ; the carapace 

 is markedly distinct by its trapezoidal outline, deep ventral region, and mucronate 

 antero-dorsal angle, which was not nearly so often lost in f ossilization as the front 

 angle of G. papilio. In its rostrum, maxillae, superficial ornament of carapace and 

 of body-rings, it seems to have closely resembled G. papilio. In twenty-two good 

 specimens from Lesmahago, two are simply carapaces ; seven have body-segments 

 in place and thirteen have them shifted or reversed. In this respect G. stygia 

 seems to have been scarcely less Uable to the dissolution of the membranous 

 attachments of the body than its associate G. papilio. 



A postero-dorsal fragment in Cambridge Museum (Marr CoU.), from the 

 Denbighshu-e series (Wenlock), at Dinasbran, Llangollen, showing fine striae above 

 and coarse strise below, and the usual convergence of striae, belongs probably to 

 G. stygia. 



An anterior moiety of a valve, probably of G. stygia (from near Ludlow ?) is 

 in the Grindrod Coll., Oxford Mus. G. 



Good specimens of G. stygia from Lesmahago are Cambridge Mus. 6/136, 6/65 

 (the last is referred to as G. papilio, evidently by mistake, in the ' Catal. of the 

 Cambrian and Silur. Fossils of the Woodw. Coll.,' 1873, p. 178) ; M. P. G. x ^, 

 Jj, X iL, X J^, X J^, X ^; and B. M. 41898, 45154, 45155, 45156. 



In the ' Mem. Geol. Surv. Scotl. Expl. Map 23,' 1873, at p. 49, Mr. R. 

 Etheridge, junr., enumerates the places near Lesmahago and Muirkirk, in Lanark- 

 shire, where Geratiocarides have been found by the Surveyors, namely — 



Ceratiocaris papilio, Salter, at Dunside (Logan Water), Baghnside Burn, Logan 

 Water (2 miles south of Lesmahago), and Linburn. 



Geratiocaris stygia, Salter, at Kip Burn (Logan Water), Eaglinside Burn, and 

 Linburn. 



Geratiocaris, caudal appendages, at Long Burn (Logan Water), Dunside (Logan 

 Water), Logan Water (6 miles south-west of Lesmahago), Lann Burn, and Douglas 

 Water. 



There are some fine specimens of G. stygia in the Glasgow University Museum 

 and the Geological Survey Museum, Edinburgh, from Lesmahago ; very many in the 

 Braidwood Museum (Dr. J. R. S. Hunter) ; and a few also in the Edinburgh 

 University Museum, all from the same district. We have not yet been able to have a 

 selection from these figured for the Palseontographical Society, but we hope to do 

 justice to them before long and to some possibly new species associated with 

 them. 



Abdominal segments and appendages probably belonging to G. stygia are : 



B. M. 58878, Linburn, Muirkirk. A telson, not quite perfect at base, 35 mm. 

 long, associated with some obliquely-striate segments. 



B. M. 41899, Lesmahago. Four segments, 27 mm., and M. P. G x ^c, 



