ON THE DEVELOPMENT OF LICHENOPORA VERRUCARIA. 119 
because of the variation in the size of colonies at the same stage 
of embryonic development, and partly because, in comparing 
the measurements of entire colonies with those of sections, 
something must be deducted from the former series of measure- 
ments. The calcareous lamina which borders the entire colony 
is usually not very apparent in sections, or may become some- 
what crumpled. In correlating the entire colonies with the 
sections it will be well to notice that sections of colonies in 
Stage E give no evidence of an aperture belonging to the 
ovicell. 
Special attention may here be directed to the fact that a 
brown body may often be seen in the occluded zocecium of an 
entire colony. That brown body is of course the fertile brown 
body; and the fact that it may be visible in a dry colony 
when other zocecia are not seen to possess a similar structure 
is of course due to the constant occurrence of the fertile brown 
body near the original orifice. If brown bodies are present in 
the other zoccia, they are usually placed at the end of the 
cecum of the stomach, and are consequently deeply placed in 
the colony, in a position where they cannot be seen. 
The fertile zocecium to which fig. 29 refers has yet one 
further point of interest. Atashort distance below the embryo 
its cavity is completely divided by a septum which passes trans- 
versely to the long axis of the zoecium. This septum, which 
is commonly noticed in, and is indeed probably a normal 
feature of, later stages as well, is probably calcareous during 
life. It cuts off the proximal, empty end of the zocecium from 
the distal end which contains the embryo. 
Stage F.—Commencement of Embryonic Fission. 
This stage is by far the most important of all, as demon- 
strating the fundamental identity of the developmental pro- 
cesses in Crisia and Lichenopora. Fortunately there is no 
stage in the latter in which my evidence is clearer than in this 
one. I have obtained some twenty-seven series, any one of 
which by itself would have been almost sufficient to prove the 
occurrence of embryonic fission. 
