166 H. C. SORBY. 
matter genealogically, it is quite possible that by the oblitera- 
tion of the lumen of gastro-vascular outgrowths of the primitive 
alimentary canal a large bulk of cellular elements should 
be furnished to the so-called ‘‘ mesoblast ” from the hypoblast, 
and that subsequently this solid mass of cellular elements 
should by splitting develop a celom. In this way it is con- 
ceivable that the schizoccelous condition might develop from 
the entero-cclous and gradually lose all trace of its ancestral 
origin further than is afforded by the derivation of some 
mesoblastic cells from hypoblast. At the same time there is 
much to be said in favour of the schizoceelous condition being 
an aboriginal one, since we see that it really can make its 
appearance (in a rudimentary way) among Ceelenterata. The 
grouping of animals by Professor Huxley (loc. cit.) according 
tothe actual mode of formation, and supposed corresponding an- 
cestral distinction, of the body-cavity, which term has,according 
to his view of the matter, been applied to three very distinct 
kinds of cavities, cannot but draw increased attention to the 
actual and possible relationships of the spaces which develop 
between endoderm and ectoderm. Until there are facts to 
hand to show that it 7s more probable that the varieties of 
body-cavity in such groups as Mollusca, Vertebrata, and Che- 
tognatha, are of distinct origin in each cases than that they 
are due to modification of one ancestral cavity, one is disposed 
to adopt the hypothesis of uniformity as the simplest and the 
least likely to lead into difficulties. 
On the CoLounine Matter of Bonellia viridis. By H. C. Sorsy, 
F.R.S., &c., Pres. R.M.S. 
SomE months ago my attention was called by Mr. E. 
Ray Lankester to a green colouring matter which he had . 
obtained when at Naples from the above-named annelid. I 
immediately saw that it was a substance of great interest, 
and in order that I might be able to study it carefully Mr. 
Lankester kindly gave to me a large portion of the material 
he had collected. He has since furnished me with the notes 
and drawings which he made at the time, and with the 
following description of the animal, which it would be well 
to give before entering into the consideration of the optical 
characters of the pigment itself. 
Bonellia is a worm which lives in holes in calcareous rocks. 
