PERCID^E. 11 



Genus III. Acerina, Cuvier. 



Gymnocephalus, Bl. Schn. : Cemua, Flemming. 



Branchiostegals seven : pseudobranchice present. Opercle and preopercle spinate. 

 Distinct muciferous channels on the liead. Teeth in jaws villiform : absent from the 

 palatine bones and tongue. A single dorsal fin with many spines (13 to 19) : anal 

 with two. Scales ctenoid, and of moderate size, none on the head. Pyloric appen- 

 dages few. Air-bladder simple. 



Geographical distribution. The fishes of this genus are found in the rivers of 

 the Palasarctic region, extending from Siberia and Russia as far south as Northern 

 Italy. It has been remarked that their distribution is limited to rivers or waters 

 which have their outlet in the Arctic Ocean or into European seas, similarly to 

 the distribution of Perca fluviatilis. Irrespective of the Acerina cemua there are 

 two other European species, the long-snouted A. Schrcztzer, with distinctly 

 longitudinal bands, and a variety, A. rossica, in which these bands are indistinct 

 or even absent, this fish is found in rivers flowing to the Black Sea : also the 

 A. czelcanowshii from the River Angera. 



1. Acerina vulgaris, Plate III. 



Cemua fluviatilis, Belon. Aqu. p. 291 ; Gesner, pp. 191, 192, 226 ; 

 Willughby, p. 334 t. X 14, f. 2 ; Ray, p. 144. Perca fluviatilis minor, Gesner, 

 pp. 29, 701, 825 f. 160 a and 161; Schonev. p. 56 ; Aldrov. v, c. 34; Jonston, De 

 Pise. lib. iii. t. 3, c. 2, t. xxviii ; Ray, p. 144, Perca, Artedi, No. 3, 

 Spec. p. 80 and No. 4, Genera, p. 40 ; Klein, Hist. Pise. No. 1, v, p. 40 ; 

 Duhamel, Peches iv, p. 39, t. viii, f. 1 ; Marsigli, iv, p. 67, t. xxiii, f. 2. Buffe, 

 Pennant, Brit. Zool. (Ed. 1) iii, p. 259, (Ed. 2) iii, p. 350. 



Perca cemua, Linn. Sys. i, p. 487 ; Gronov. Zooph. p. 86, No. 288 ; Schceffer, 

 Pise. Bavar. Ratis. Pentas ; Bloch, t. liii, f. 2 ; Gmel. Linn. p. 1320 ; Donovan, 

 Brit. Fish, ii, pi. xxxix ; Shaw, Zool. iv, p. 548, pi. 79 ; Turton, Brit. Fauna, 

 p. 100; Jenyns, Man. Brit. Zool. p. 334; Miiller, Zool. Dan. Prod. p. 392; 

 Gronov. ed. Gray. p. 112. 



Gymnocephalus cemua, Bl. Schn. p. 345 ; White, Catal. Brit. Fish, p. 12. 



Perca acerina, Bonnaterre, Ency. Ich. p. 134, pi. liii, f. 205. 



Holocentrus post, Lacep. iv, p. 357. 



Cemua fluviatilis, Flemm. Brit. An. p. 212. 



Acerina vulgaris, Cuv. and Val. iii, p. 4, pi. xli, vii, p. 448 ; Fries och Ekstrom, 

 Skand. Fish. p. 9, t. i, f . 2 ; Yarrell, Brit. Fish. (Ed. 1) i, p. 18 c. fig. (Ed. 2) i, 

 p. 17, (Ed. 3) ii, p. 122 ; Cuv. Reg. Anim. 111. Poiss, pi. ix. f. 2. ; Nordm. in 

 Demid. Voy. Russ. Merid. iii, p. 368 ; Gunther Catal. i, p. 72 ; Houghton, Brit. 

 F. W. Fishes, p. 5, c. fig. 



Acerina cemua, Gunther, Wiegm. Archiv. 1855, p. 199, pi. x, f. 1, 2 ; Collett, 

 Norges Fiske, p. 16. 



Buff, Couch, Fishes of the British Isles, i, p. 193, pi. xli. 



B. vii, D ^Jhr, P. 13-14, V. 1/5, A. T %, C. 18, L. 1. 40, L. t. 6/14. Ccec. pyl. 

 3, Vert. 15/20-22. 



Length of head 3f to 3, of caudal fin 5J to 6|, height of body 3| to 3f in 

 the total length. Eye diameter 3% to 4 in the length of the head, 1 to If 

 diameters from the end of the snout, and f of a diameter apart. Body compressed, 

 a concavity on the dorsal profile above the eye and occiput causing the snout to 

 appear swollen. Upper jaw slightly the longer : the posterior extremity of the 

 maxilla reaches to beneath the front edge of the eye. Opercle with a well 



