Cretaceous Chipeoid Fishes. 491 



(2) Ctenothrissa radians, Ag., sp. 



Originally referred to Beryx by Agassiz (Poiss. Foss. 

 vol. iv. pp. 4, 118, pi. xiv. 6. fig. 7, pi. xiv. c. rigs. 7-9). 

 Several specimens of this species in the British Museum 

 exhibit the typical Clupeoid head, one (no. P. 5699) being 

 especially well preserved and displaying the minute teeth 

 both on the maxilla and premaxilla. None of the fin-rays 

 are spinous, the appearance of a pelvic spine in the type 

 specimen, as described by Agassiz, being proved by other 

 specimens to be deceptive. The species attains a length of 

 about 0'25 m., and may be briefly defined thus : — Head with 

 opercular apparatus relatively smaller than in C. vexillifer, 

 and marked with a fine rugose ornament. About 40 ver- 

 tebrse. Pelvic fins with 7 or 8 stout rays, which, when ad- 

 pressed to the trunk, extend to the anal fin ; anal fin with at 

 least 12 rays, arising opposite the hinder end of the dorsal 

 fin. Scales very finely pectinated; lateral line extending 

 along the ninth series above that which forms the ventral 

 border of the flank. Common in the Lower Chalk of 

 England. 



(3) Ctenothrissa microcephala, Ag., sp. 



Originally referred to Beryx by Agassiz (torn. cit. pp. 4, 

 119, pi. xiv. b. figs. 3-6, pi. xiv. c. fig. 10). As in the two 

 preceding species, so in this, the British Museum collection 

 demonstrates the presence of a Clupeoid head and the absence 

 of fin-spines. This fish is rather elongated and attains a 

 length of about 0*15 m. The length of the head with oper- 

 cular apparatus equals the maximum depth of the trunk and 

 is contained about twice in the length from the pectoral arch 

 to the base of the caudal fin. Fins apparently as in C. ra- 

 dians, but the pelvic fins less elongated. Scales relatively 

 large and coarsely pectinated ; lateral line extending along 

 the fourth series above that which forms the ventral border 

 of the flank. Common in the Lower Chalk of England. 



Pseudobeeyx, Pictet and Humbert. 

 [Nouv. Recli. Poiss. Foss. Mt. Liban, 18G6, p. 32.] 



Definition. Head and opercular apparatus as in Cteno- 

 thrissa. Vertebras approximately 30 in number, half being 

 caudal. Paired fins small, the pelvic pair inserted opposite 

 the dorsal, which is short- based and nearly median ; anal fin 

 smaller than the dorsal ; caudal fin deeply cleft. Scales 

 pectinated, large and regularly arranged, none enlarged or 

 thickened, and no dorsal or ventral ridge-scales. 



Type. Pseudoberyx syriacus, Pict. & Humb. (op. cit. p. 33, 

 pi. ii. figs. 4-6). 



