NATURAL HISTORY MISCELLANY. 311 
can compare in any sense with that of the Polyzoa; and in trans- 
forming the Polyzoon into an Ascidian, Prof. Allman is obliged to 
violate this obvious difference, as well as to effect many sai’ 
which are not consistent with their organization. The ne 
affinity of the Polyzoa and Brachiopoda is hardly inal 
since the investigations of Koraleusky, who has shown us that 
the young Ascidians are apparently more like young vertebrata 
than they are like the young of the Polyzoa. The importance 
and value of the resemblances existing between the adult Poly- 
zoon and the adult Ascidian, so far as they may be supposed to 
indicate any close affinity or community of origin are thus doubly 
denied by the differences of form and structure, both in the adults 
and in the larvee. 
The Ascidians are also likely to be removed by these new dis- 
coveries, not only entirely away from the Polyzoa, but to an equal 
or greater distance from all the rest of the Mollusca; and even if 
we could in the face of embryology still maintain our comparison 
between the two structures, we should be contrasting the Polyzoa, 
not with a typical Mollusk but with an animal whose own position 
is very uncertain. I can think of no fundamental molluscan char- 
acteristics, either in the Brachiopods or Polyzoa, which ally them 
with the Lamellibranchs (clams), except those which join them 
still more closely to the Ascidians. Therefore it seems clear, that 
if we separate the Ascidians from the Lamellibranchs, which they 
so closely resemble in their general adult characteristics, on ac- 
count of their different developments, we must also, in turn, remove 
the Polyzoa from the Ascidians, and should logically regard the 
similarities of the two as analogies arising in different structures, 
and not as affinities derived from some common ancestor. Thus 
cut off from its quondam molluscan allies our Polyzoon has but 
one refuge ; its development points concisely to a vermian ances- 
tor, and to this source we must relegate both it and its nearest 
ally, the Brachiopod. 
Prof. Morse called attention to the fact that Koraleusky, Heckel, 
Darwin and others had pointed out the relationship apparently 
seen in the embryo of certain Tunicates, and the typical idea of 
the vertebrate embryo. Without expressing an opinion for or 
against this view, it was interesting to remark that many eminent 
naturalists had seen reason to include the Tunicates with the Ver- 
mes; and in the supposed relation, on the other hand, of the Tu- 
