H. JAMES-CLARK ON THE AFFINITIES OF SPONGES. 321 



plasticity is even more marvellous than that of Codosiga ; at least it is exhibited over a far 

 wider lateral range than in the latter, and with equal rapidity in its changes. In a few sec- 

 onds it narrows from its greatest expanse to the proportions of an obverted, acute-angled 

 cone (fig. 29, b), and at the same time assumes an altitude which is equal to the length of 

 the body ; and then, within an equally short period, it contracts into the form of a cylin- 

 der (fig. 30, b) whose height more than equals that of the calyx. These changes are car- 

 ried on with the same peculiar vibrations as were noted in regard to Codosiga, reminding 

 one of the glimmering outlines of the prongs of a tuning-fork when vibrating. When 

 observed witli a poorly defining lens, I can readily see that this phenomenon might be mis- 

 taken for the cone of light produced by the gyratory vibrations of a single filament, or for 

 the bright lumen of a circular row of vibrating cilia. As regards the former category it 

 may be said that the flagellum is far more conspicuous than the collar, and may be seen 

 clearly projecting in the line of the axis of the body, and vibrating after a manner of its 

 own. As for the latter supposed case, one might be inclined to dismiss it without any scru- 

 ple, upon the simple assumption that no flagellate infusorian can bear numerous cilia, were it 

 not that I call to mind my own discovery of a flagellated animalcule (Heteromastix, figs. 70— 

 74) of the heteronematous form, which is at the same time abundantly ciliated. I have, 

 therefore, taken all possible pains to ascertain that this " collar " (figs. 28-32, b) is a genuine 

 membrane, and not the similitude of one. 



Occasionally individuals (fig. 32) were seen which bore an inverted conical collar (b), that 

 remained — at least for a time — at an expansion and altitude equal to the breadth and 

 height of the calyx (c). These were among the largest specimens found, and almost or 

 altogether filled the calyx. Rarely were examples found which crowded the calyx so fully 

 as to seem to bulge it out laterally. Figure 31 represents such an instance, in which the 

 aperture (c 1 ) of the calyx is absolutely inseparable from the head, excepting that, knowing 

 that it is not really continuous, one recognizes the line of demarcation by the abrupt change 

 in the thickness of the seemingly uninterrupted membrane. This case is also remarkable, 

 inasmuch as it at the same time furnishes us with an example of an enormously large, bulg- 

 ing, campanulate collar, nearly as broad as the most common and normally permanent form 

 (fig. 28), and yet higher than it is wide. In all probability, judging from appearances, which 

 in every respect remind one of the preparatory steps of fissigemmation of Codosiga pidchcr- 

 rimus, this individual is soon about to undergo self-division. Unfortunately the drawing was 

 made at a time when the impending process could not be watched. 



The flagellum (fl) is as highly flexible as that of & gracilis, and ver}' active throughout its 

 length. It is attached to a more or less elevated axial prominence in the middle of the 

 frontal area, and extends to a length which is, at most, not more than one third greater than 

 that of the body. 



Regarding the digestive organs nothing can be said, excepting that dark irregular pellets 

 and loose foreign material were abundant enough, and so irregularly scattered that they 

 could not be looked upon otherwise than as nutritive matter. 



The contractile vesicles (cv) are two or three globular bodies, which in appearance, position, 

 relative size, and rate of systole, may be compared with those of Codosiga pukherrimus. On 

 one occasion (fig. 30), they amounted to four (cv) in number, and were arranged in pairs, one 

 above the other. 



The calyx (c, c 1 ) usually has the form of a Florence flask, but with a very short, thick 



MEMOIRS UOST. SOC. NAT. HIST. Vol. [. I't. 'i. 5 



