CERAMURUS. Ill 



The pelvic, dorsal, and anal fins are rather well shown in the type specimen 

 (PI. XXII, fig. 4), which also retains fragments of the pectorals and caudal. 

 The former appear to agree in all respects with the corresponding fins of P. 

 purbeckensis, being only slightly smaller in proportion to the depth of the trunk. 

 The scales are also evidently similar to those of the earlier species just mentioned. 

 In both specimens they are much fractured, and nearly all are exposed from the 

 inner face, displaying the strong vertical rib, with the peg-and-socket articulation 

 in the abdominal region. They are, however, clearly smooth and without posterior 

 serration. 



Horizon and Locality. — Upper Purbeck Beds : Upway, near Weymouth, Dorset. 



Genus CERAMURUS, Egerton. 



Ceramurus, P. M. Gr. Egerton, in Brodie's Fossil Insects, 1845, p. 17. 



Generic Characters. — Trunk slender fusiform, and head relatively large ; noto- 

 chord persistent, surrounded with spaced ring-vertebra? ; ribs short and delicate. 

 Fin-fulcra few, long and slender. Pectoral and pelvic fins long, but few-rayed ; 

 dorsal and anal fins not extended, the former in advance of the latter ; caudal fin 

 long, but probably somewhat forked. Squamation absent on flanks, except, 

 perhaps, a rudiment anteriorly ; a short series of robust ganoid ridge-scales on both 

 borders of the hinder half of the caudal region. 



Type Species. — Ceramurus macrocephalus, irom the English Purbeck Beds. 



1. Ceramurus macrocephalus, Egerton. Plate XXII, fig. 7. 



1845. Ceramurus macrocephalus, P. M. Gr. Egerton, in Brodie's Fossil Insects, p. 17, pi. i, fig. 2. 

 1895. Ceramurus macrocephalus, A. S. Woodward, Greol. Mag. [4], vol. ii, p. 401; and Catal. Foss. 

 Fishes, Brit. Mus., pt. iii, p. 489. 



Type. — Nearly complete fish ; British Museum. 



Specific Characters. — A slender species, at least 4*5 cm. in length. Length of 

 head with opercular apparatus nearly twice as great as the maximum depth of 

 the trunk, and contained about four-and-a-half times in the total length of the fish. 

 Pectoral and pelvic fin-rays about equal in length : dorsal fin with about 10 rays, 

 opposed to the pelvic pair ; anal fin with 8 or 9 rays, completely behind the 

 dorsal. Caudal ridge-scales smooth, those of the upper border especially acumi- 

 nate, each being produced into a long point. 



Description of Specimens.— This species is known only by three specimens : 

 the type discovered in the Middle Purbeck of Dinton, Wiltshire, by the Rev. P. B. 

 Brodie (shown enlarged in PI. XXII, figs. 7, 7a) ; a more imperfect fish discovered 



