EL, J. Clark.—Tubularia Not Parthenogenous. 65 
about by a simple hollowing out of the ovigerous stratum, so that, 
instead of remaining a solid mass, it becomes as it weré a lining 
to the muscular layer, which embraces it. Thus in an end view 
of the bud we would have a hollow sphere made up of five con- 
centric layers, succeeding each other as enumerated above. This 
is essentially the typical form of the meduso-genitalium of the 
ubularians; for whatever changes occur in the later days of 
growth, no new morphological features are instituted 
? On the walls of the most highly developed medusoid—The immense gelatini- 
form mass which constitutes such a large proportion of the bell of these free forms 
u 
layer, chondrophys ; 8d, the outer muscular stratum, ectomyoplax, which presses 
ophragma, in eon the mesophragma of | bell 
Now in the fally-formed ¢ meduso-genital of the above mentioned Tubularians, T. ig 
&c., only the chondrophys is wanting. ms ect and endoderm 4 
gladly adopt for, yet would restrict to, the outer and inner walls of the ccenosare 0 
hydratorm ; b it would seem to be a misapplication of terms to call the 
middle wall,” of the meduso-genital or gonophore, a derm, I apply to it the name 
and 
