150 
$ 
G. HERBERT FOWLER. 
cup thus formed is to be regarded, therefore, as belonging to the 
former, the inner side, which carries the spheeridia, to the latter. 
The structure of the cup can be gathered from the schematic 
figure 14 without further description. The thickness of the 
mesogloea appears to be characteristic of the whole animal. 
The sphaeridia, the degenerate representatives of the ten- 
tacles, call for little remark ; they are hemispherical ampullae 
(figs. 13, 14, sph.), scattered irregularly over the oral disc, 
communicating by a passage narrower than their diameter, 
with either inter- or intra-mesenterial chambers. No dis- 
tinction into cycles is possible, no special musculature is 
recognisable. In a specimen not figured they were rather 
more numerous than in fig. 12, and set more regularly in 
rows corresponding to particular mesenterial chambers. They 
are covered by simple columnar epithelium, are devoid of 
nematocvsts, and present no terminal pore. 
The stomodseum exhibits a slight structural variation from 
the normal type ; it is marked internally by a series of tongue- 
like ridges produced by inward growth of the mesogloea and 
ectoderm, the endoderm taking no part in their formation 
(fig. 13). They do not correspond to mesenteries or mesen- 
terial chambers. No siphonoglyphe is recognisable. 
The mesenteries in the most perfect specimen amounted, to 
twenty-three pairs, at and below the plane of the oral opening, 
of which twelve were complete, and comprised the first two 
cycles, while the remaining eleven pairs may be referred to an 
incomplete tertiary cycle. Near the lip of the cup, at least 
fifty pairs were present, so that in this, as in some other genera, 
new mesenteries take origin just under the oral disc, and not 
in the angle between body wall and pedal disc. 
Only one pair of directive mesenteries could be determined 
by transverse sections of the most perfect specimen ; a second 
pair was perhaps present, but unrecognisable owing to the 
slight development of muscle on many of the mesenteries. 
While in many cases the mesogloea lamina of the mesenteries 
is reduced to a thin refringent line, in others it forms, at the 
plane of the contorted edge of the mesenterial filament, a 
