ASCIDIA. 73 
2nd. It shows us the true position of the Ascidians 
(Tunicata) in the animal series. If we knew only the 
adult forms we might regard them as being an aberrant 
eroup of the Vermes, or possibly as occupying a position 
between worms and the lower Mollusca, or we might place 
them as an independent group; but we should certainly 
have to class them as Invertebrate animals. But when 
we know the whole life-history, and consider it in the 
light of ‘‘recapitulation”’ and ‘‘ evolutionary’’ views, we 
recognise that the Ascidians are evidently related to the 
Vertebrata, and were at one time free-swimming Chordata 
occupying a position somewhere below the lowest Fishes. 
N.B.—In an account of this nature, in which I have 
obviously made the fullest use of the published works 
of my predecessors, I have not considered it necessary 
to burden the text with frequent references to original 
memoirs. While accepting, then, full responsibility 
for my statements—nearly all of which I have taken 
occasion to verify by personal observation—I do not, 
of course, claim any originality in regard to them. 
Several excellent bibliographies of the Tunicata have 
_ already been published : another seems superfluous. 
