89 JOURNAL OF THE 
pockets) extending into the velum (as velar canals). Co- 
nant does not dwell on phylogenetic inferences, but evi- 
dently inclines to the belief that the ancestors of the Cu- 
bomedusz possessed a margin divided into sixteen lobes. 
The present position of the four sense organs indicates 
the site of the original margin, ‘‘which elsewhere has 
erown down and away from its former level, leaving the 
sensory clubs like floatage stranded at high-water mark.”’ 
Fusion between adjacent lobes, involving the ectoderm 
and jelly, gave to the medusa a continuous margin and a 
‘velum’, but, owing to the incompleteness in the fusion 
of the extodermal linings of the several lobes, the latter 
still retain in the adult Cubomedusa enough of their in- 
dividuality to indicate their former condition. In a word, 
the marginal pockets of the existing Cubomeduse are to 
be construed as entodermal linings of once separate lobes. 
This conclusion as to the morphology of the marginal 
pockets derives much support from the behavior of a puzz- 
ling structure, called by Conant the marginal lamella. 
Unlike the true vascular lamella, which simply connects 
one entodermal cavity with another, the marginal lamella 
extends from the entoderm of the gastrovascular space 
to the ectoderm of the bell margin. It is a narrow strip 
which follows the outline of the marginal pockets, trav- 
eling in the radii of the sense organs far away from the 
actual edge of the bell, and surrounding the sense organs 
in such a way as to indicate clearly that they were once 
at the bell margin. The marginal lamella seems to be 
a functionless, rudimentary organ, Claus, whose imper- 
fect description of the structure did not bring to hght its 
morphological interest, as indicating the site of the an- 
cestral bell margin, suggested that it was perhaps the 
vestige of a ring canal. Conant naturally is skeptical of 
this explanation of a lamella connecting ento- and ecto- 
derm. The true meaning of this peculiar lamellaisa 
