46 ACANTHOPTERYGII. 



extremities or not so, the length of the ventral fin, situation of the lateral-line 

 and position of the vent, appear to be subject to considerable variations in this 

 genus, even in the same locality, yet they have been accepted by some ichthyo- 

 logists as reasons for according specific rank, whereas others have only deemed 

 them to be varieties or sub-species. As in examples of this genus these variations 

 are not always permanent ones, I have considered them to be varieties, as only in 

 permanence of variation can species be admitted. 



Geographical distribution. — Arctic regions of Europe, Asia and America, also 

 North Atlantic Oceans of both hemispheres descending into temperate zones : 

 found both in salt and fresh waters. One or two species have been recorded from 

 Japan. 



Cottus gobio, Plate XIX, fig. 2. 



Boeroc, Arist. iv, c. 8. 



Ghabot, Belon. p. 213. Cottus, Rondel, ii, p. 202. Cottus fluviatilis, Gesner, 

 f . 162 a ; Aldrov. v, c. 28, p. 613 ; Willughby, p. 137, t. H. 3, f . 3 ; Ray, p. 76. 

 Gobio capitato, Jonston, De Pise. lib. iii, t. i, c. 10, Art. xi. Kojjpe, Gronov. Zooph. 

 No. 270 ; Cottus, sp. 1, Artedi, Gen. p. 48, spec. p. 82, synon. p. 76. Cottus Imvis; 

 Marsigli, Danub. iv, t. xxiv, f. 2. Percis, sp. Klein, Mss. v, p. 43, No. 17. Biver 

 luUhead, Pennant, Brit. Zool. (Ed. 1) iii, p. 216, pi. xxxix, (Ed. 2) iii, p. 291, 

 pi. xliii ; Bowdich, Brit. E. W. Fish. No. 24. 



Cottus gobio, Linn. Syst. i, p. 452 ; Eabr. Eauna Groenl. p. 159 ; Gmel. Linn, 

 p. 1211 ; Gronov. Mus. Ich. ii, p. 14 ; Bloch, t. xxxix, f . 1, 2 ; Bl. Schn. p. 61 ; 

 Lacep. iii, p. 252 ; Donovan, Brit. Eish. iv, pi. Ixxx ; Turton, p. 94 ; Shaw, 

 Zool. iv, p. 254, pi. XXXV ; Jurine, Poiss. Lac Leman, pi. ii ; Cuv. and 

 Val. iv, p. 145 ; Eleming, Brit. An. p. 216 ; Ekstrom, Fiske Morko, p. 167 ; 

 Fries och Ekstrom, p. 34, t. vii, f. 2 ; Tarrell, Brit. Eish. (Ed. 1) i, p. 56 c, fig. 

 (Ed. 2) i, p. 71, (Ed. 3) ii, p. 48 ; Jenyns, Brit. Vert. p. 343 ; Swainson, Pishes, 

 ii, p. 271 ; Thompson, Nat. Hist. Ireland, iv, p. 80 ; Giinther, Neckarfische, p. 17 

 and Catal. ii, p. 156 ; Gronov. ed. Gray, p. 103 ; Nordm. in Demid. Voy. Buss. 

 Merid. iii, p. 376 ; White, Catal. Brit. Fish. p. 6 ; Schlegel, De Dieren van 

 Nederl. p. 46, pi. v, f . 3 ; H. Maka, Weigm. Arch. 1864, p. 272 ; Blanchard, 

 Poiss. France, p. 161, c. fig. ; Houghton, British E. W. Eish. p. 7, c. fig. 



Cottus minutus and ventralis, Cuv. and Val. iv, pp. 152, 194. 

 ,, tricuspis, Reinh. sen. Kgl. D. Vid. Selsk. Nat. Math. Afhand. B. 5, 

 p. Iii, 1829-30. 



Cottxis poecilopus, Heckel, Ann. Wien. Mus. ii, 1839, t. viii, f. 1, 2 ; Nordm. in 

 Demid. Voy. Buss. Merid. iii, p. 377 ; Gunther, Catal. ii, p. 157. 



Cottus affinis, Heckel, Ann. Wien. Mus. ii, p. 145, t. viii. 



,, micro stomus, Heckel, 1. c. ; Nord. 1. c. iii, p. 377 ; Heckel and Kner, 

 Susswasserf. p. 32. 



Cottus ferrugineus, Heckel and Kner, 1. c. p. 34. 



Miller s thumb, Couch, Eish. Brit. Isles, ii, p. 6i pi. lix. 



Phohetor ventralis. Collet, Norges Fiske, p. 30. 



B. vi, D. 6(-8) I 16-17 (18), P. 14, V. 1/4, A. 12 (-14), C. 11. Coec. pyl. 4, 



Vert. 10/23. 



Length of head 4 to 4c\, of caudal fin 6\, height of body h\ in the total 

 length, pjyes — supero-lateral, placed just anterior to the middle of the length of 

 the head and 1 diameter apart. Head broad and depressed, while the gill-covers 

 are generally found distended, showing this still more clearly after death : behind 

 the head the body gradually decreases in size and becomes laterally compressed. 

 Cleft of mouth shallow, its gape wide : the posterior extremity of the maxilla 

 reaches to beneath the middle of the eye. Upper surface of the head covered 

 with a soft moveable skin, which has numerous minute elevations encircling the 

 opening of pores, the same being continued to over the first third of the body. 

 A rather strong, backwardly-directed spine exists at the angle of the preopercle 

 and occasionally another at its base : a strong forwardly- directed spine at the 

 anterior-inferior angle of the subopercle : no other spines on the head. Anterior 



