)60 



SCANDINAVIAN FISHES. 



irrep'uliir rows, the outermost row coutaiiiiiig the largest 

 teeth both in the uiijx'r jaw and the lower. A similar 

 .eard of teeth, set across the palate and eurved, occupies 

 the head of the ^•olner. The upper pharyngeals on each 

 side form two disks, crowded -with fine, rather blunt 

 teeth. The anterior disk is nai-row and of uniform 

 breadth, tlic posterior (on the two hind pharyngeals, 

 which are coalescent) large and (juadrangular 'with- 

 rounded corners or cresceiit-shai)ed. The cards of teeth 

 on the lower pharyngeals are oblong. Th.e four bran- 

 chial arches are furnished with short, spiny protuber- 

 ances instead of gill-rakers. The gill-openings ai-e 

 large. The brancliiostegal membrane is nioderatclv in- 

 cised underneath, with a narrow, fi'ce, dermal margin 

 across the isthmus. The whole head is clotlied -with a 

 thick, mobile skin, loosely attached to tiie body, and 

 entirely coyering and concealing the opercidnr bones. 

 In structure the scales of the Tadpole Fish very 

 closely resend)le those of the ])receding geiuis. Tliev are 

 furnished ex'clusiyely with concentric, denticulated stria; 

 (ridges). (hi the other haml, the nucleus is usually 

 yerv large — though sometimes reduced in the extreme 

 — and oidA' the Aounger (smaller) scales haye continuous 

 striie, following the elliptical or oblong outlines of the 

 scale. In other cases tliev are more or less interrupted 

 at l)oth ends of the scale, in the anterior (inserted) 

 part to ]('n\G room for a longitudinal, smooth patch at 

 the middle, as a continuation of the nucleus, and in 

 (he posterior (free) part of the most developed scales 

 to <'Oi-i'espoMd to the configuration of the truncate mar- 

 gin of the .scale. This margin is furnisiied with a 

 greater or less niunlu'r of teeth — KnnYEii has counted 

 as many as 18 — and here the said stria' partly i-un 

 straight out to the margin, and partly scattei- into small, 

 irregulai', yei'miform, transverse stria". We must re- 

 nuunber, howeyer, that these ciliate teeth at the hind 

 margin of the scales are often wanting: in some speci- 

 mens we haye failed to discover any of these ciliated, 

 truncate scales, while in others they apparently occur 



slime, wliich entirely conceals the scales, and renders 

 the Avhole surface of the skin smooth and shiny. The 

 lateral line, which is only slightly marked, and forms 

 a small curve in front, is hardly distinguishable during 

 the life of tlie fish, but in specimens that have long- 

 been preseryed in s])irits, this curve ap])ears as a row 

 of light-coloured protuberances". 



The vent is large and thick-lip|)ed. with an anal 

 papilla behind it, and is situated just in front of the 

 beginning- of the anal fin. 



The pectorrd tins are fairly large, their length being 

 about 15'' — 17 % of that of the body, and arc I'ounded 

 at the tip. Their basal part is somewhat elongated 

 (brachiate), and their rays, of which the middle ones 

 are longest, an' thick at the base and at the tip very 

 regularly divided into 8 branches, running ])arallel to 

 each other. 



The yentral tins are set farther forward than the 

 pectoral, at a distance from the beginning of the anal 

 fin of about 18\'2 — 22 % of the length of the body. 

 They contain t! ravs, the first two being nuich longer 

 than the others and furnished Avith long, free, fila- 

 mentous ti])S, arched in a forward direction. The se- 

 cond ray is the longest, sometimes measuring as much 

 as IS',', % of the length of the body. The four inner 

 rays ai-e small, closely united, and branched, but witli 

 the tips themselves as it were coalescent. 



The first dorsal fin, wliich begins at a distance 

 from the tip of the snout measuring in young speci- 

 mens 26—28 %, in old 29—33 %, of the length of the 

 body, is only rudimentary. It is set in a deep groove 

 formed b^- the dorsal edge, and is composed of one 

 large, distinct, simple ray, which is, however, short, its 

 length being always less than the longitudinal diameter 

 of the eye, and behind which we find two extremeh' 

 small and indistinct ra-\s. The latter rays can often 

 be distinguished only with the help of scalpel and mag- 

 nifying-glass. The second dorsal fin begins just Ijehind 

 the ]ierj)endicular from the base of the pectoral fins. 



oi 



dy on the hind part of the body. The scales on that at a distance from tiie tip of the snout of about 31 



part of tiie body which lies behind the vent, are also 

 more regulai'ly arranged and flat, but on the for('])art 

 of the body as well as on the head the^■ are more 

 irregular, rathei' more depressed, and as it were concaye. 

 During life the fish is coated with a thick layer of 



36 % of the length of the body. It is of almost uni- 

 form height, and I'uns along the back for a distance 

 equal to about 49 — 54 % of the length of the body, 

 to the yery base of the caudal tin, the space between 

 these fins being extremely small or hardly perceptible. 



" "Above fill- pcct(jrnl tins, on eticli t^ide, was ii row of tulicrrlps from wliicli coiuineiioi'd tlie lateral liitf. wliicli was (iniilw.iy) iii- 

 curvatod": Pennan'I', 1. c. 



'' In our largest spoeiinen 14. 



