60 Miscellaneous. 



jaw ; and at the base of the tail, below the vertebral column, the 

 pulsating movement of the blood passing from behind forwards in 

 the subcaudal veins can be distinctly recognized. 



The eyes of our animal are smaller than in the normal state, and 

 therefore appear rudimentary. They are reddish violet ; their back- 

 ground is without pigment, so that it appears red ; on the other 

 hand, dark pigment exists in an equatorial zone (taking the normal 

 axis of the eye as axial) ; of course, however, these conditions can- 

 not be ascertained with perfect certainty in the living animal. 



As the yellow colour of this eel has remained unaltered to the 

 present time (20th September, 18S0) we have in it an example of 

 the very rare case of leuccethiopism in a fish. Although the other 

 yellow eels were at the first glance very like the one just described, 

 they have proved very difl:ereut from it in their whole behaviour. 

 All had black spots upon a lighter or darker ground, and these spots 

 were distributed either only upon the upper part of the head, or also 

 over parts of the back. The eyes were always normal. In size 

 the animals did not essentially differ from the first-mentioned eel. 



The thirteen animals of this kind received by our aquarium in the 

 course of the year 1879 all changed their colour by the winter ; 

 they gradually became darker and darker, until at last they had 

 acquired the coloration of normal eels. This is the more remark- 

 able as there were among them animals which, with the excejition 

 of the blackened head, were perfectly pure yellow, exactly like the 

 above-described albino. The nine eels received by our aquarium 

 this summer (18S0) were likewise spotted with black upon a yellow 

 ground. As yet they have not changed colour. 



Similar yellow black-spotted eels have been observed several 

 times besides the present cases. In the literature of the subject I 

 find only one case. Erandt (Bull, de I'Acad. de St. Petersb. vol. x. 

 1852, p. 13) and von Siebold (Siisswasscrfische von Mitteleuropa, 

 p. 19, note) mention an eel presented by Dem. Taghoni to the Paris 

 Museum, which was pale brownish yellow (nankeen-yellow) and 

 normally coloured only at the extremities of the nose and tail. The 

 colour of the eyes is not stated in the description given by Meuuier 

 (in D'Orbigny's Dictionnaire d'Hist. Nat. tome i. 1841, p. 249). 

 Brandt calls this the only example of a leucotic fish. 



According to an oral communication, Prof. Mobius, of Kiel, re- 

 ceived a similar female eel, fully ^ metre long, on the 29th May, 

 18G8 ; the animal had normal eyes. 



According to a report in the public papers another eel of the kind 

 was recently taken in a piece of water to the south-east of Bremen. 

 In answer to a letter of inquiry addressed to the [former] possessors, 

 MM. F. Klevenhusen & Co., of Bremen, those gentlemen have given 

 me the following information about this fish : — The eel was exactly 

 the colour of a goldfish and had black eyes ; it had four or five 

 black spots in the neighbourhood of the head ; the belly also was 

 darker than the back, so that in water it appeared as if the eel was 

 lying on its back. The animal has been presented to the Bremen 

 Museum ; in spirit it has lost its red colour and become yellow. 



