oel lia?; I)o<>oino rcmiHl, fnt. fk'sliy. mul nnifli liit;liov (lin.ti lioforc; rompare 

 ]i;irtiful;irly tlie Ik-joIiI nlmvc llio poclorals in di-dcr tn luive ii hnsis i'or t,lie 

 coiiiparison; tlio ]irolile ol' tlii' ocfiput luis tims ln^foiiio (|uile aiiotlior. It 

 poems tliat tlio lips generally hecome a little smaller Avliile those ohanges take 

 l)hu-c, liiit if is ilitticull in dcciilc tliis (|UPsti(m 'on acfouiil ol' tlie s^roat 

 individual variation; oiie tliing howovcr lias remained nnaltored : liie iiitcr- 

 orbital spaee. On tlic wliole, i do not believe tliat tliis transformation ol the 

 lioad cxtends to tlie ixniy cranium: it is eertainly tlie soft ]iarts oidy wlndi 

 prodnc'O tho whole transformation Irom l'rog-raouthed cel to silver eel. 



It will snrely he granted tliat tliis transformation from an ajqioai^anee 

 likc lig. 1 to anotlier ajipearance like tig. 4 is striking. and it will easily lie 

 imderstood tliat tlic lishormen have noticed tliese two lorms, or mort' cor- 

 rectly, the former of them; for they do not distinguish tlie latter from otlier 

 silver eels witli a narrow interorbital space; they all go hy the name of 

 sharp-nosed eels; for between tig. 3 and 4, plate J, there is neither liabitually 

 nor gastrononiically the difference as between these and the frog juonthed eel, fig. 1 . 



If we look at tlie heads of the smaller eels which are represented (also the 

 males), we shall observe tliat some similar ehanges have taken place; it is liere 

 ]iartienlarlv the enorinous eyes which tend so much to chauge the appearance. 



We mnst not imagine, however, that it is only the membrane covering 

 the eyes which grows largei- in the silver eels; already tig. (i a, plate II, 

 shows that the proHle has direetly changed its form by an eulargement ol 

 the apple of the eye. and by taking ont the eyes I have seen, moreover, that 

 the very apple of tlie eye really grows larger. By weighing the eyes after 

 (hey were taken ont and, as well as possible, cleared of the appendant 

 mnsclcs and nerves, I found in ayellow and a silver female eel of respectively 

 20-^/, and 20 inches that the eyes of the yellow eel weighed 75 mgr. (and 

 measnred ;")• ^ """), and that those of the silver one weighed 170 mgr. (and mea- 



snreil 7' ., , and in a yellow and a silver male eel, lioth 14V,, inches in lengtli. 



that the eyes of the yellow one weighed 40ingr. (and measm-ed 5 '"'"), and tliat 

 Ihose of the silver eel weighed 80 mgr. (and measnred 6 """). These were far 

 from representing extreme cases, rather below the average. 



On the said Hgnres representing heads of yellow and silver eels we can 

 f urther sce_tliat /læ ntmijicafmis of tlic UiUral line are more distinct on the 

 silver eels than on the yellow ones, and that the pecloiaJ-s of all silver eels, 

 though somewhat varied in form, nndoubtedly are more ])ointed behind than 

 those of the yellow ones, and that they, compared to the length of the head, 

 are longer on the former than on the latter; f urther, the pectorals of the 

 vellow ones are l>right-coloure<l, those of the silver eels dark, eveu black. 



