28 
Or the presence ør absence of a duct from the swimming bladder 
to the æsophagus in fishes can it be found preserved in a fossil 
state? Further, the mouth parts of insects, the radula of snails or 
the gills of the bivalve mollusecs — can these structures be found 
in fossil specimens? Such perishable structures must be left out 
of consideration in classification, — "because it is impossible to 
understand the recent forms without an exact knowledge of their 
fossil ancestors or predecessors”. 
Perhaps Lambert will maintain that his first sentence: ""parce 
que le test d'un Échinide n'est pas comme celui d'un mollusque, 
une simple enveloppe et seulement un tégument protecteur des tissus 
mous; C'est encore un véritable squelette trahissant Vorganisation 
compléte de VYanimal” indicates that the conclusions derived above 
are not allowed, his meaning being that his new principle is to be 
adopted only for those forms, where the structures preserved by 
fossilization represent a true skeleton, indicating the whole organi- 
zation of the animal. Let us accept this for a moment and see 
what the results would be. CertainlyLambert will not deny that 
the condition is perfectly realized by the Vertebrates and the Arthro- 
pods, even if it be an external skeleton in the latter; consequently 
Lambert must widen his classifieatory principle to embrace also, 
at least, these divisions of the animal kingdom, and the results, 
which need not be specified, bear out splendidly the value of the 
new principle. 
An alternative is still left. In the work of Boule and 
Thevenin quoted above Lambert says: "il ne faut pas appli- 
quer a des animaux inférieurs, dont les organes sont moins spécia- 
lisés, une méthode qui peut étre excellente pour des étres trés 
évolués et perfectionnés”. We will concede for a moment that the 
remarkable new principle should only be applied to the lower ani- 
mals. The consequences, however, are no better. Take the Holo- 
thurians for instance; probably Lambert will agrée that they are 
at least as "low” as the Echinoids. They must then only be 
Classified on the basis of their skeletal plates; their anatomy must 
