24 



liow eagerly tho flapsifioatioii ol' tlio eol lias bopii sttidied. or nt nnv intc liow 

 iiiucli tliere has beeii written on it, 



()n the one liaiul iho fshprmen liave alwavs kiioA\n tbat tliere were hvo 

 very diil'erent form.« o)' eels, tlie yellow and tlie silver eel^, hiit \ve caiiiiot ex- 

 peci llieiii lo give a i'iirtlier explaiiatioii ol tliis faet; on tlie otlier liand most 

 {'lin/iil Ki/stemcili.ils liave seen tliat all our forms of eels doubtless beloiig- to 

 one species, and tbis I think is also correet; tlierefore tbey bave not eared to 

 eliter iiito a study of tbe two forms of eels; other (niihom bave not seen tiiis 

 and bave uncritically set up tbe forms tbey bave got from tbe Hsbermen as 

 species, and bave tbus got 2, 3, or even more species. In our own literature, 

 fiii- iiistancc. H. Kroi/P)\ in -Danmarks Fiske, bas set nji 3 species: I. ^1;/- 

 (liiilhi migraiorin. Ivrøyer, wliicli evidently corresponds to tbe large, sil ver eels 

 witb a liroad interocular space; II. Angirilln ariifirosfris'r' Yarrell, correspond- 

 ing to tbe middle-sized, balf silver, still yellow-tinted eels (tbe fignre is ttikeu 

 from Yarrell and is evidently a picture of a silver eel), . and finally III. An 

 (liiilhi Idtiroftris, Yarrell? corresponding to tlie meager, yellow eels (tbe fignre 

 from Ydrrcll and represeuting a frog-moutbed eel). 



Tlie latest great Scandinavian work on the fishes, LiUjehorg: »Sveriges 

 ocb Norges Fiskar. , makes one species out of Krøyer's three, and justly so, but 

 w'itbout explaining wliat tlien is tlie reason why these forms exist. In Eng- 

 land wbere Yarrell in bis time in British Fishes« also set up 3 species: 

 Angiiilla anitirm^frls. A. lafirostris, and A. mediorostrif:, corresponding to Blank- 

 aal, Kla'paal og alm. f/idr Aal or Silrer eelti. Frou-movlhed eels, and Yelloir eels, 

 later authors. as Fr. Day : »British Fishes«, 1880— S4, have also looked upon 

 these forms as belonging to one species, Imt witbout giving sufficient reasons 

 for it; his statements vol. II, p. 242, are jiartly wrong, partly insufficient. 

 England's well-known ichthyologist A. Giinfher, on tbe other band, bas, 1870, 

 in bis -f'afalof/iie uf llie Fishes iii Ihr British Mnsenni'-'- , vol. \'III, tried to dis- 

 tinguisb between tbe two species: A. vulgaris aiid lafirosfris: the latter, evi- 

 dently, is founded only on yellow females and corresponds exactlyjto tbe »frog- 

 moutbed eel«, (»Glut« or »Grig«). Neitber the position of tbe fins, the lengtb 

 of tbe head, the size of the lips or the eyes, nor the breadtb and lengtb of tbe 

 snout can be used as specific characters, for all tran.sition-forms are found be- 

 tween the extremes. — In France and Gerniany the antboi-s rather agree in 

 believing in one species of eels in Europe, and Vaniillelhiresle: »liésimié (rane 

 Movogr. des Poissons Angnilli formes. Arcb. de Zool. exjier. etc Tom. IV. 

 IHTf) bas arrivcd at the same result, \\v.. tbat Ibc form of tbe head 



