﻿148 ICHTHYODORULITES. 



of Erismaeanthui, but cannot be certainly determined. The spine 

 is laterally compressed, gently arched, tapering, and ornamented 

 with fine superficial tubercles. 



The imperfect Ichthyodorulites from the Lower Carboniferous of 

 the United States, described under the names of Gampsacanthus, 

 St. John & Worthen (Pal. Illinois, vol. vi. 1875, p. 471), and Lecra- 

 canthus, St. John & Worthen (ibid. p. 475), appear to be fragments 

 of ErismacantJi us-shaped spines. To the former "genus" are as- 

 signed G. ? latus, St. John & Worthen (ibid. p. 474, pi. xxii. fig. 14), 

 from the Keokuk Limestone of Missouri : G. squamosus, St. John & 

 Worthen (ibid. p. 473, pi. xxii. fig. 13), from the Upper St. Louis 

 Limestone of Missouri ; and G. typus, St. John & Worthen (ibid. 

 p. 472, pi. xxii. fig. 12), from the Upper St. Louis Limestone of 

 Illinois and Missouri. Lecracanthus has only a single species, L. 

 unguiculus, St. John & Worthen (ibid. p. 476, pi. xxii. figs. 10, 11), 

 from the Upper St. Louis Limestone of Missouri and Illinois. 



A fragment, probably of a similar nature, from the Lower Car- 

 boniferous Limestone of Armagh, forms the type of Dipriacanihus, 

 F. M'Coy (Ann. Mag. Nat. Hist. [2] vol. ii. 1848, p. 121), with 

 the single species, D. stokesii, F. M'Coy (ibid. p. 121, and Brit. 

 Palaeoz. Foss. p. 627, pi. iii. x. fig. 18), noticed later by J. W. Davis, 

 Trans. Eoy. Dublin Soc. [2] vol. i. (1883), p. 360, pi. xlviii. fig. 10. 

 [Woodwardian Museum, Cambridge.] 



Genus LISTRACANTKUS, Newberry & Worthen. 

 [Pal. Illinois, vol. iv. 1870, p. 371.] 



Spine small, gently arched, and much laterally compressed, ex- 

 panding and abruptly truncated at the base. Sides ornamented 

 with numerous acute longitudinal ridges ; the concave and convex 

 margins provided with many divergent, slender denticles, pointing 

 towards the apex of the spine. 



The type species is L. hystrix, Newberry & Worthen (torn. cit. 

 p. 372, pi. ii. fig. 3), from the Coal-Measures of Illinois and Ohio \ 

 Spines from the Upper Carboniferous Limestone Series of Mons, 

 Belgium, are also assigned to this species by L. G. de Koninck 

 (Faune Calc. Carbf. Belg. pt. i. 1878, p. 75, pi. v. fig. 11), and the 

 following specimen resembles the latter : — 



47307. Spine 0-015 in length, but wanting the apex ; Castiaux, 

 near Mons, Belgium. In this specimen the alternate 



1 J. S. Jvewberry, Rep. Geol. Surv. Ohio, vol. i. pt. ii. (1873), p. 337, and 

 ibid. toI. ii. pt. ii. (1875), p. 66, pi. hx. fig. 5. 



