170 
SCANDINAVIAN FISHES. 
THE RIVER BULLHEAD (sw. stensimfan). 
COTTUS GOBIO. 
Plate VIII, fig. 1. 
Among the hones of the head only the suboperculum and preoperculum f urnished with spines , and only the upper- 
most, preopercular spine distinctly prominent, forming a hook pointing upwards in a posterior direction, and cur- 
ved inwards, the second spine scarcely projecting above the skin, and the third apparent only as a tubercle. The 
spine at the lower corner of the suboperculum is directed forwards, but scarcely projects above the skin a . The 
distance, which increases with age, between the anal fin and the tip of the snout, in adult specimens at least, is 
never less than 48 % of the length of the body , and the length of the base of the fin is under 48 % of this dis- 
tance. The innermost ray of the ventral fins measures more them half their length. Branchiostegal membranes 
united to and separated by the isthmus. The length of the maxillary bones is greater in the male than in the 
female and varies between about, 24 and 35 % of the length, of the base of the second dorsal fin: the length, of 
the lower jaw, which is subject to the same difference according to sex, varies between 33 and 44 % of the length 
of the base of the same fin. 
R. hr. 6; D. 7 * — 9| 1 6 — 18 ; A. 11 — 13; P. 13 1 11; 
V. V 4 ; C. « + 8 1. 9+«; L. lat. por. 33 — 36. 
Syn. Cottus alepidotus glaber, capite diacantho, Art., Gen., p. 48, 
Syn., p. 76; Spec., p. 82. 
Cottus capitatus , Lin Mus. Ad. Frid., vol. I, p. 70. 
Coitus Gobio, Lin., Syst. Nat., ed. X, tom. I, p. 265; Fn. Suec., 
ed. 2, p. 115; Retz., Fn. Suec. Lin., p. 329; Cuv., Val., Hist. 
Nat. Poiss., vol. IV, p. 145; Ekstr., Vet.-Akad. Handl. 1831, 
p. 308; Nilss., Prodr. Ichth. Scand., p. 98; Ekstr. et 
Wright, Stand. Fish., ed. 1, p. 34, tab. 7, fig. 2; Kr0Y., 
Damn. Fiske, vol. 1, p. 141; Sundev., Ofvers. Vet.-Akad. 
Fork. 1851, p. 185; Id., Stockh. L. Hush. Sallsk. Handl., 
1855, p. 179; Nilss., Skand. Fn., Fisk., p. 64; Gthr, 
Cat. Brit. Mus., Fish., vol. II, p. 156; Sieb ., Susswasserf. 
Mitteleur., p. 62; Mgrn, Finl. Fisk., p. 4; Ltkn, Vid. Meddel. 
Naturli. For. 1865, p. 218; Lindstr., Gotl. Fisk. (Gotl. L. 
Hush. Sallsk. Arsber. 1866) p. 14 (sep.); Blanchard, Poiss. 
d. eaux douces de la France, p. 161; Malm, Gbgs, Boh. • 
Fn., p. 387 ; Feddersen, Naturh. Tidskr. Kbhvn , ser. 3, vol. 
XII, p. 73; Day, Fish. G:t Brit., Irel ., vol. I, p. 46; Lillj., 
Sv., Norg. Fisk., vol. I, p. 125; Mor., Hist. Nat. Poiss. 
Fr., vol. II, p. 293; Mob., Hciie, Fisch. Osts., p. 48. 
Cottus affinis, LIeckel, Ann. Wien. Mus. Naturg., vol. 2 (1836), 
p. 146. 
Ohs. In his Systema Natures (1. c.) Linnzeus has overlooked 
the circumstance that four years before he had called this species 
Cottus capitatus, deriving the specific name from Gesner (Gobio flu- 
viatilis capitatus) De Aquat., p. 477. 
This species and the following one are the smallest 
of the true Cotti in Scandinavia. The usual size of the 
River Bullhead, when full-grown, is between 75 and 100 
mm., though specimens have been met with up to a 
length of 125 mm. c . Small as is its importance in an | 
economical respect, its interest from a scientific point of 
view is nevertheless great, partly for its breeding habits, 
and partly for the differences between it and its rela- 
tives, wherein it represents the transition from the 
genus Cottus to Callionymus, Gobius etc. 
The body is of the usual round Cottoid-form, ta- 
pering like a cone posteriorly: the sides of the tail are 
somewhat compressed. The head, the length of which 
varies between 25 and 27 % of that of the body, is 
depressed and broader than the trunk, but, like that of 
the following species, differs from the others in the 
following respects: it is entirely without projecting 
spines or knobs and has no trace of the elevations 
which appear in the other Cotti on the top of the head. 
It is thus rounded evenly at the top towards the sides 
and the snout, which is also rounded anteriorly, and 
flatter underneath. The eyes are set on the slope, 
somewhat nearer the snout than the occiput, and at a 
distance from each other which in adult specimens may 
indeed be externally equal to the vertical diameter of 
the eye, but if we measure only the least interorbital 
breadth of the frontal bone, is at most V 2 the hori- 
zontal diameter of the eye. They project considerably 
and are turned somewhat upwards* 2 , a circumstance 
which causes the profile of the head to appear com- 
pressed behind the eyes. The gape is broad and almost 
horizontal and the jaws project equally, but the upper 
a The spine which is situated at the lower posterior corner of the interoperculum and directed backwards, is present, but is extremely 
indistinct. 
1 Sometimes 6 according to Valenciennes and Lill.teborg, or 5 according to M6bius and IIeincke. 
c Mobius and IIeincke say even 150 mm. 
d Hence the name of Uranidea, with a reference to the resemblance to Uranoscopus (Gronov., Mus., 2, No. 166; Dekay, 1. c.). 
