27 



that tlie spiiiy lurvæ beloiig to Z. pmidulnK, |irubably betuiise tliey have a 

 large iiuiiil)er of ravs, and bo is uot tonviiiced by M'Iutosh's argutneuts. 

 Holt, cousec|uently, gives up his oiigiual opinion, that tiie spiny larva 

 sliould 1)6 tilt" youug of Z. norvcgictis, and rel'ers it to Z. pHiicUitns ou the 

 streugth of Cimninghum's investigatious. He does not venture, however, 

 to speak with auy greater decision about this matter. 



As will be seeu from the above, the number of Hnrays has been of 

 great importance in the wliole argumentation as to the determination of 

 these larvæ '). In itself it is a dangerous thing to rely too mucii upon tlie 

 number of fin-rays; firstly, beeause only a very small number of specimens 

 of these species has been examined, and, secoudly, beeause the number of 

 rays in these tishes varies uot a little. 



LUljehory states for Z. pundatns: d. 87 — 101 ; a. 80 — 69; vertebræ36 — 37, 

 Z. megastoiiia: d. 91 — 85; a. 75—61; » 41, 

 Z. norvegicHs: d. 84— 79; a. 67— 58; » 34—352), 

 Z. tinimaculafus: d. 80 — 70; a. 68 — 61. 



It will be seen that there is here a great variation within the species, 

 and tilis variation, no doubt, will be still greater when a larger uumber of 

 specimens are examined, particularly if they come from differeut localities. 

 The number of vertebræ does uot seem to promise much either. It is 

 necessary at any rate that a larger uumber of specimens are examined 

 before any thing eau be decided. In a Z. pundatns I have counted 9 + 26, 

 and in a Z. norvegicus 9 + 25 vertebræ. 



Although the number of fin-rays, as a character, must thus be used 

 with judgment by the determination of the grown-up Zengoiiteriis, this is 

 so much the more necessary where the young fish are concerned, which 

 have not yet, perhaps, got all their fin-rays, and about which, at any rate, 

 we do not know for certain if they have. I shall therefore, for a moment, 

 leave this matter out of cousideration. 



In the seas within the Skaw there live only two species of the genus 

 Zeugopterus, viz. Z. pundatus and Z. norvegicus. Of Z. megastoma oul}' one 

 specimen has been taken in the SkagerRaek, in 1868 (according to Malm). 

 It must certainly be exceedingly rare there, and I doubt that it occurs 

 there normally'). Z. unimaculatus has uever been seen in Denmark or 

 Scandinavia. 



When, nevertheless, we Hud in the Cattegat the above mentioned two 



') By the terui larva I indirate all the young .stages whit-h have not yet got the 

 form of the grown-up fish; consequently, as a rule till the persistent pectoral rays appear 

 and the eyes have got the same form as in the grown-up fish. All pelagic stages there- 

 iore are larval stages. 



'-') According to niy own investigation. The cither numbers of the verteliræ are 

 from Smitt's "Skand. Fiskar". 



■'') Cmp. Collett: "Meddelelser om Norges Fiske". Clu'istiania Videnskabsselskabs 

 Forhandlingei- for 1903, No. 9, p. 89. 



