REPRODUCTION AND METAMORPHOSIS OF COMMON BEL. 377 
Here I must particularly insist that I have ascertained in 
an absolute manner that during the metamorphosis of the 
Murenoids the number neither of the myomeres, nor of the 
vertebral arches, nor of the spinal ganglia is subjected to any 
change. The hypurals of Leptocephalus brevirostris are 
precisely the same as in the elver of Anguilla vulgaris, 
The last hypural which is fused with the urostyle may pre- 
sent itself as a single piece, or may be more or less cleft, 
These are variations which are met with also in the elver. 
Just as in the elver, the last hypural but one is always ex- 
tensively cleft, or, if the expression is preferred, doubled. To 
the last hypural correspond five rays, whilst four correspond to 
the last but one, and one to the last but two, the whole 
structure being identical with that found in the elvers of 
Anguilla vulgaris. Of these ten rays, the eighth, seventh, 
and sixth are bifid, both in Leptocephalus brevirostris and 
in the elvers of Anguilla vulgaris. In the pectoral fin of 
Leptocephalus brevirostris the definitive rays can be ob- 
served, and these are of the same number asin the elvers of An- 
guilla vulgaris. Leptocephalus brevirostris is transpa- 
rent, and has colourless blood. The red corpuscles are wanting, 
but there are present so-called ‘ blood-plates” (“Blutplattchen” 
in German) similar to those of the inferior Vertebrates. The 
bile is also colourless. This fact is observed in all the other 
Leptocephali. Leptocephalus brevirostris is, however, 
the only one which is free from all pigmentation. Corre- 
spondingly, the common eel is the only species of Murznoid 
which at the close of metamorphosis (i.e. in the youngest 
elvers) is devoid of all trace of larval pigmentation. It was 
this observation which first led us to the discovery of the 
relations between Leptocephalus brevirostris and An- 
guilla vulgaris. 
In making transverse sections of Leptocephalus brevi- 
rostris I found other characters which confirm the relation 
between it and the common eel; for instance, the branchio- 
stegal rays are ten to eleven in number, as is also observed in 
the elvers of Anguilla vulgaris. In the common eel the 
