708 



SCANDINAVIAN FISHES. 



mouth and belong to the thick part of the li]_). On the 

 lower jaw too, the lij) runs back in a dermal fla[) on 

 each side. This flap, as IvRt^YER" has already pointed 

 out, may now and then be denticulated or even pro- 

 duced at some spot so as to resemble a barbel, thus 

 depriving the above-mentioned generic difference be- 

 tween Cohitis and Misgurnus to some extent of its 

 validity. The intermaxillary bones are small and nar- 

 row, ^vith the main branches only slightly longer than 

 the straight nasal processes. The maxillaries, on the 

 other hand, are high and of singular form. Behind the 

 articular knob they exi)aiid into a s(juare, but again 

 contract, and at the hind extremity once more expand 

 into a rounded lobe curved in a downward direction. 

 In the upper jaw we find a well-developed palatal fold. 

 There is no free tongue. On the first branchial arch 

 the gill-rakers are set in a single row (containing 11 — 

 14) corresponding to the posterior row on the other 



Fig. 177. Right lower pliaryngeal of a Cohitis tania, seen from 

 witliin and abo%-e. About 15 times tlie natural size. 



arches, where they are set in a double ro-\v, and on the 

 lower pharyngeals in one row (containing 7) on the outer 

 anterior margin of these bones. Thej^ are short and 

 depressed. The pharyngeal teeth are subulate, pointed, 

 and curved; they are set in a row (10 or a few moi'e, 

 3 of wiiich lie on the upper arm) on the inner (posterior) 

 margin of the lower pharyngeals, which are geniculate, 

 like branchial arches. Sometimes, however, we find one 

 or two smaller teetli (suppleinentary teeth?) l)eside the 

 principal row. The gill-openings are merely vertical 

 slits, the branchiostegal membrane on each side of the 

 body coalescing with the skin at the anterior end of 

 the insertion of tiie pectoral fin. The height of the 

 opening is about equal to the thickness of the head at 

 the eyes; but the branchiostegal membrane is loose, the 

 gill-openings being thus capable of exi)ansion by means 

 of the three long, sal)re-like brancliiostegal rays on each 



side. The preoperculum extremely narrow, the other 

 opercular bones well-developed. The liind inferior 

 margin of the operculum proper is cui'ved in an S-shape, 

 with the anterior lower corner produced in a downward 

 direction, but the breaks are filled b)' the suboperculuiii. 

 As we have mentioned above, the head is scaleless; but 

 the ducts belonging to tjie system of the lateral line 

 are usually quite distinct on its surface, being marked 

 by rows of small pores, often raised in a tubular form, 

 along the temples, straight across the occiput, along the 

 ])reo])erculum and the branches of the lower ja^^•, on 

 the forehead and at the upper orbital ratirgin on each 

 side, and along each of the cheeks, below tiie slit con- 

 taining the preorbital spine and for^vard on the snout 

 below the nostrils. 



The body, on the other hand, is densely covered 

 with small, round, thin, imbricated, cycloid scales. The 

 lateral line is distinct onlj- at the very beginning, where 

 it forms a backward continuation of the temporal canal, 

 first sloping dowuM'ards and then straight, for a distance 

 of about twice the longitudinal diameter of the eyes. 



The dorsal fin is obliquely rectangular, with the 

 upper angles rounded, the upper posterior margin being 

 thus more or less convex. Its base is somewhat elevated 

 in front, forming a sliglit l)reak in the otherwise straight 

 contour of the back. Its beginning lies at a distance 

 from the tip of the snout that measures about 41 — 43 

 % of the entire length of the body, 47 — 50 % of the 

 length of the body mimis the caudal fin, or 67 — 6o % 

 of the distance between the anal fin and the tip of the 

 snout, and is generally situated somewhat in front of 

 the perpendicular from the insertions of the ventral fins. 

 At its origin we find two rudimentary, unarticnlated 

 rays (supporting rays), the first extremely small, the 

 second about one-third as long as the third ray. The 

 third ray is simple (undivided) but articulated, and 

 only slightlj' shorter than the fourth, which is the 

 longest ray in the fin and, like the remaining rays, 

 branched. The last ray is about half as long as the 

 longest one, and there is no fin-membrane behind it. 

 The shape of the fin is highly inconstant, the length 

 of its base (on an average about 8'/ 2 % of the length of 

 the body*) varying between 64 and 76 % of its heigiit 

 (the length of the longest ray). 



The anal fin is of the same structure and siiajie as 

 the dorsal, onlv that the branched ravs ai'c fewer and 



■■ Damn. Fishe, III, p. 568. 



'' Varying, according to Canestrini's measurements, between 7'2 and 10 ". of tlie length of the body. 



