878 



SCANDINAVIAN KISHES. 



(|ii;i(lraiigtilai- s1im]io, witli .soiiu'whiit (mjiivl'X upiier nuir- 

 ,iiiii, and witii the liimliiiost ray iiieasuriiig about " ., 

 of the longest ray. The shape and structure of the 

 adipose tin have already been noticed. It is situated 

 above tlie posterior tlnve-fiftlis of tiie base of the anal 

 tin, but tlie distance Ijetween it and tlie caudal fin 

 (about 7 — 11 % of tiie lengtli of the body) is in ge- 

 neral perceptibly greater than tiiat between the anal 

 fin and the latter. Tiie anal tin begins at a distance 

 fi-oni tiie articular Icnolis of tiie inaxillaries in the males 

 equal to about " ,. (IKi — <-i8'/2 -^*)' '" ^'ic^ females nearly 

 '/, (71—72' , %). of the lengtli of tlic Ijody. The 

 sexual difference in the base of this tin we have al- 

 ready remarked. The length of its base is in the males 

 about 17 — lil %, in the females aliout 13 — 15 %, of 

 the length of the body. Its lower margin is arcuate, 

 and its height (the length of the longest, the 5th or 

 nth ray) is always less than half" (8S-47 %, exeep- 

 tionalh- 49 %) of its length (base). The caudal tin is 

 as a rule somewhat less deeply forked than in the 

 Smelt, the length of the middle rays being aljout 43 

 — 53 % of that of the longest ones and usually greater 

 fh;in the least depth of the tail, only exceptionally, 

 and then in the males, ecjual to the latter. The length 

 of the middle rays varies between about h^',., and 6 '/a 

 % (exceptionally 7 %), and the lengtli of the longest 

 rays lietween about 12 and 14 %, of that of the liod)'. 

 The pectoral tins are set low, as in the Smelt, 

 and the great sexual difference lies not oid}% as we 

 have mentioned above, in the length of the tins, but 

 also in their breadth. In the males, when the tins are 

 folded, one of them overlaps the other under the Ijelly 

 to a considerable extent. When expanded, the two 

 fins together form in the males almost a semicii-cle. 

 In the females they are of a broad oval shape. Their 

 length varies in the males between about 15'' iind 

 IG'/s %i in the females between about 10 and 13' ^j %, 

 of that of the body. As a rule even their relative 

 length increases with age, the females thus representing 

 the lower grades of development. The ventral fins 

 resemble the ])ectoral Itoth in shape and sexual dif- 

 ference, though the latter is less marked, and the 

 ventral fins of the males together compose, more cor- 

 rectly speaking, a half-ellipse. Their length is also on 

 an average equal to that of the pectoral. Thev are 



inserted almost \ertically below tlie beginning of the 

 true dorsal fin, comjwratively further back in Aoung 

 Capelins than in old and in the females than in the 

 males, the average preabdominal length being in young 

 females 31 V'^ %, in old females 32'/2 %, in the males 

 30' ., %, of the length of the bodv, and the average 

 postabdominal length in the females 18' ^ "&, in voung 

 males 18'/., %, in old males 17' ., %, of the length of 

 the body. 



The scales are thin and small, as we ha\e men- 

 tioned above, but in essential respects (fig. 220, u) re- 

 semble those of the Smelt, both as regards shape and 



m 



mJ 



Fig. 220. Scales from the loft side of a Mallotiis villosiis, I2V2 

 times tlie natura] size. (/, one of the ordinary scales below the lateral 

 line in a female; i, a scale from the lateral line of a female: c, one 

 of the larger scales at the base of the anal fiii in a male; (/. one 

 of the villiform scales in the lateral band of a male, with the epi- 

 dermal coverine^ preserved, and witlt lobes of the lorn dermal follicle 

 (coriiim) or eacli side. 



texture, onlj- that the concentric striix- are fe^v and 

 scattered (usuallv no more than 5 or 6 l)ehind the 

 indistinct nucleus of the scale, 3 in front of the same), 

 and interrupted at the top and bottom of the scale. 

 The scales of the lateral line (&) have the same open 

 incision in the hind part, and the duct is simply cana- 

 liculate, nowhere closed by the elevated margins. The 

 rule for the growth of the scales in the lateral line 

 being that the duct is at first canaliculate, these .scales 

 accordingly occupv in the Capelin a lower develop- 

 mental rank than in the Smelt. In the males, as we 

 have mentioned above, scales of a special shape appear 



" In the Smelts always greater, 68 — S4 'i, in Osmeriis epcrlamw. 



'' In exceptional cases wc have foiuid the pectoral fins of a male to measure only 14'7 '„ of tlie length of the body. 



