13 ' 



Silver females. Silver males. 



Tifl;il wuijilit. Miyi'slivc iirj;;iiis Si'Mial nif;;nis, 'l'ijliil \\i'i^;lil. I>i^'ustivi' urgaiiH Scxiuil mgaUH. 



;uiil air liliidiUr. and iiir-l)la(l<ler. 



I \n\\v ineiitioucd seveml distiiictive niurk.s, botii cxteriial and iuk'nial, 

 wliich (lif<tiugui.sh thc yellow eels from the silver eels, Imt it must Ix' said also 

 tliat tlicse mark.s prettv ofteii ure insuttieieut, and tliat \ve are tlieret'ore some- 

 times lel't in doubt whetlier \ve are to ])Iace an eel in the l'ormer or the kitter 

 ol' tlit^se categories. This is oltene.st the case with kii'ge female eels; wu can 

 here easily lind all transition-l'ornis from yellow frog-mouthed eels to shilling 

 fiilly eharadenzed silver eels: to this I sluill return later on. But also 

 aiiKing the smaller eels transition-l'ornis ran he ])niiite(l out, particularly in 

 salt water in after-suunner. 



The Silver Eels. 



W'luit liefore all characterizes the silver eels is thc form of their snout 

 and the situation of the eyes ou this (lig. 8, 4, (i, 7, piates I & II). The 

 snout jjcforc the eyes is not (juite Hattened in the silver eels as in the 

 yellow ones. but it is liigli and a little comjiressed, j)robably owing to the 

 consiilerable developmciit of the olfactory organ and the size of the eyes. 

 Aniong thc males (tig. tj iV 7, plate 11) tliis height of the snout is exceedingly 

 sti'iking, l)ut a comparison hctween the large yellow females and the large 

 silver females shows something similar. 



This, cvidcntly. is thc basis of C. V. Ekstiomt^ 2 species: Muræna (tji/rliina 

 and Mn)fi)i(i pl(it]ijir]ii)ui. oi wliich the former corresponds to the silver ccls, 

 the latter to thc yellow ones; the former, moreover, has a small, the latter a 

 larger anus. They are cvidcntly rather based on the fishermen's knowledge tlian 

 011 J-Jhstroiii'i^- own investigations, and the tisherraen always distinguish (in ull 

 oountries) between the yellow and the silver eels. The zoological view on the spe- 

 cies, on thc othcr haiid, is all the .same to them. That many otln-r autiiors have 

 looked upon this ditfereut form of tiic snout as a specific character will he 

 mentioned afterwards. 



The situation of the eyes of the silver eels is such that they, when 

 wc look at tiie head vertically from above (tig. 3, 4, ti, & 7 (b), piates I & II), 



