310 Proceedings of Royal Society of Edinburgh. 
ABBREVIATIONS. 
II. = mesomere. 
III. = metamere. 
1. l'l = protocoele. 
2. 2'. = mesoccele. 
3. 3'. = metacoele. 
I. = protomere. 
pi. = prototroch. 
ms. t. = mesotroch. 
mt. t. — metatroch. 
pt.p. = protocoelic pore. 
ms. p. == mesocoelic pore. 
mt. p. =-- metacoelic pore. 
Addendum . — Since the above was read I have, through the 
courtesy of Professor Schinskewitsch, had my attention called to a 
paper read by him before the International Congress at Moscow in 
zoaires. In this he attempts to bring together very much the 
same groups as I have done above, and in a similar manner he lays 
emphasis upon the divisions of the coelome. He, however, derives 
them from a common ancestor, the Enterocoelula with one pair of 
<e sacs coeloiniques,” and regards the subsequent divisions into two 
( Tentaculiger ), and later into three, as secondary, whereas the 
essential part of the above theory is that the divisions are primary 
and comprise a form of segmentation which the Metazoa owe to 
their descent from axially (radially) symmetrical animals. I have 
been able to add a number of morphological and ontogenetic facts 
which have become known since 1892, and feel justified in leaving 
the term Archi-Ccelomata as emphasising the views here expressed 
of archimeric and metameric segmentation. 
1892, Sur les Relations genetiques de quelque groupes des Meta - 
