140 Prof. H. James-Clark on the Spongiee ciliate 
and often-repeated retrocession. Upon putting on a power of 
eight hundred diameters, the whole organization was brought 
out with sufficient clearness to satisfy one upon every point. 
For the purposes of illustration, however, it was thought best 
to increase the magnifying-power to a still greater extent ; and 
we have, therefore, drawn one figure (fig. 34) to represent this 
infusorian as it appears when seen under an amplification of 
about fifteen hundred diameters. . 
This animal has never been found in a free state, or in any 
other than that which is represented in these two figures 
(figs. 34, 35). It hasan elongate oval body, which is enclosed 
in a deep vasiform, pedicellated calyx (c), to whose bottom it 
is attached by a slender, colourless, contractile ligament (7). 
It usually rests about halfway between the top and bottom of 
the calyx, but is frequently jerked to the bottom (fig. 35) of 
the vase (c) by means of the ligament just mentioned. The 
anterior end is truncate, and prolonged into two prehensile 
organs, one of which is a flagellum (ft), and the other a lip (/p) 
similar in position and function to that of the Monas described 
in the previous section. The generally prevailing fuscous tint 
is interrupted by a transparent colourless streak (71), which 
extends from the laterally posited base of the flagellum (1) to 
the posterior end of the body, where it seems to be prolonged 
into the contractile ligament (7). It is not a band, however, 
but a sharply defined furrow, of considerable depth. At the 
anterior end it is sunk so deeply that it borders closely upon 
the base of the flagellum, and from that point it gradually 
shallows until it nearly disappears at the point of junction of 
the body with the contractile ligament. 
We are thus reminded of those heteronematous Flagellata, 
like Anisonema (figs. 65-69), whose bodies are so conspi- 
cuously sulcated in a longitudinal direction; and the apparent 
continuity of the retractor ligament (fig. 34, 7) with this 
furrow (r!) heightens the impression, by its resemblance to the 
highly muscular trailing lash (figs. 65-69, f#*) of that genus. 
One could hardly be accused of unduly straining a point in 
homology if he were to regard the furrow (fig. 34,71) in 
question as merely a greatly prolonged ostial notch, and the 
retractor (7) as a trailing lash, which originated at the greatest 
possible distance from the other, its proboscidal companion (//). 
The lip (dp) is a more prominent organ than that of Monas. 
It has a conical shape, and is about twice as long as its greatest 
breadth. It is so hyaline as to readily escape notice until it is 
fully recognized. It is situated at the edge of the truncate 
front opposite to that from which the flagellum arises, and 
therefore leaves a considerable space between the latter and 
