200 Prof. H. James-Clark on the Spongie ciliate 
of momentary change. Unless it be by means of the vibra- 
tions of the flagellum, there is no other immediate agent 
which can be supposed to move the body up and down in its 
sheath. ‘There is no visible movement in itself, like creeping, 
to be observed; and moreover the body progresses so quickly, 
when changing its place in the calyx, that it becomes evident 
that it is not due to any reptant mode of transposition. When 
withdrawn (fig. 38) into the basal tapering portion of its calyx, 
the collar (b) does not extend beyond the rim (c!) of the latter, 
but, on the other hand, the body occasionally moves so far in 
the opposite direction (fig. 39) that nearly the whole of the 
collar (6) projects outside of the dormitory. | 
The flagellum is a delicate filament which arises from the 
axial point of the front, and projects a short distance beyond 
the edge of the collar. It presents a constantly undulating 
aspect, and vibrates from base to tip. 
The mouth, we are obliged to presume, as we did in regard 
to Codosiga, lies somewhere about the base of the flagellum. 
Abundant digestive vacuoles were observed, as well as loose 
particles of food, in various parts of the body; but at no time 
were we so fortunate as to see the introception of nutritive 
material or the ejection of feecal matter. 
The contractile vesicles (cv) are two in number. They lie 
between the second and posterior thirds of the body, usually 
on opposite sides, and close to the surface. In aspect and rate 
of systole they resemble those of Codosiga pulcherrima, but 
they are a little smaller in proportion to the size of the animal- 
cule. Sometimes the protean changes of the body are so ex- 
tensive as to throw the two vesicles into a line with each other 
in an antero-posterior direction; but they hold this position 
only temporarily, and soon return to their normal relations. 
The calyx (c c! c*) has the general shape and proportions 
of a champagne-glass, and appears to be hollow to the very 
bottom (c*) of its pedicel-like inferier third. Anteriorly it is 
truncate, smooth, and flares (c!) quite strongly. About the 
middle it bulges very sensibly, and thence tapers gradually 
into a slender posterior third (c*), but expands again slightly 
as it terminates upon its place of attachment. It is colourless, 
excessively transparent, and exhibits considerable flexibility 
under the movements of the body, apparently having the con- 
sistency of a mere film. | 
§ 8. Salpingeca marina, nov. sp. (Pl. VI. figs. 28-32.) 
The remarkable generic resemblance of this species to Codo- 
siga has already (p. 193) been commented upon. It is very 
common, especially upon the marine Hydromedusa Dynamena 
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