86 FISH CULTURAL ASSOCIATION. 
of proportions forbids us to consider them as furnishing true 
specific characters. 
“T also think, with Siebold, that albinism and melanism, that 
is to say, the diminution or augmentation of the number of chro- 
matophores, are only individual anomalies and cannot be ranked 
as specific characters. Risso long since separated the black con- 
gers under the name Muraena nigra. Kaup described as distinct 
species many black Anguillas. These species should be sup- 
pressed. I have elsewhere proved the frequent occurrence of 
melanism and albinism more or less complete in nearly all the 
types of fishes belonging to this family, a fact especially inter- 
esting, since albinism has hitherto been regarded as a very excep- 
tional phenomenon in the group of fishes. This also occurs in 
the Symbranchide. 1 have recently shown it in a specimen of 
Monopterus from Cochin China, presented to the museum by M. 
Geoffroy St. Hilaire. 
“I must also signalize a new cause of multiplication of spe- 
cies ; it is partial or total absence of ossification in certain indi- 
viduals. This phenomenon, which may be explained as a kind 
of rachitis (rickets), has not to my knowledge been noticed, yet I 
have found it in a large number of specimens. I had prepared 
the skeleton of a Conger of medium size, the bones of which are 
flexible and have remained in an entirely cartilaginous state. 
Still it is not necessary to prepare the skeleton to determine the 
absence of ossification, for we can establish this easily in un- 
skinned specimens by the flexibility of the jaws. It is very 
remarkable that this modification of the skeleton is not incom- 
patible with healthy existence, and that it does not prevent the 
He? in which it is found from attaining a very large size. 
“Those fishes in which ossification is absent are remarkable 
by reason of the great reduction of the number of teeth, which, 
although the only parts which become hard by the deposit of 
calcareous salts, remain, however, much smaller than in individ- 
uals whose skeletons are completely ossified. 
‘“ We can thus understand how such specimens could present 
characters apparently specific, and that they should have been 
considered by Kaup as types of new species. These considera- 
