256 Prof. H. James-Clark on the Spongise ciliatas 



truly contractile, but rather flexible^ and exhibits its muscular 

 power by bending itself into coils or zigzags. Occasionally 

 specimens are met with which have an additional pair of fla- 

 gella (fig. 69,^^), of a more delicate kind, attached near the 

 others. That these originate as a preliminary step to fissi- 

 gemmation, although that phenomenon was not witnessed in 

 this case, there can be scarcely a doubt, inasmuch as it accords 

 perfectly with what has been observed in AnthojyJii/sa (p. 213). 



The mouth has not been demonstrated to a certainty, by 

 actually seeing food pass into it ; but an approximative deter- 

 mination was reached by observing particles of matter, which 

 were brought down by the prehensile Jlagellum (Jl), pass into 

 the body somewhere near the front, and apparently within the 

 compass of the covered way. 



The anus (figs. 65, 66, a) was adjudged to be at the posterior 

 end of the animal, by noticing, in a couple of instances only, 

 a clear, more or less irregular, rounded mass in this region, 

 and its final disajDpearance while under observation ; but the 

 substance was so transparent that it was not possible to decide 

 positively whether it made its exit upon the dorsal or the 

 ventral side. 



The conti'actile vesicle {cv) is a comparatively large organ, 

 with a rounded contour when in full diastole, and quite faint 

 and inconspicuous. It lies above the base of the guhernaclum 

 {fl^)j the expanded base of the latter appearing at times to 

 form a part of it, and by its movements (causing an alternation 

 in light and shade) tends to mislead one into the belief that 

 systole is very irregular. A careful adjustment of the lens, 

 however, reveals the true pulsation, and shows that the sys- 

 tole has a very slow rate. 



§ 14. Heteeomastix, Jas.-Clk.* 

 Heteromastix proteiformis^ Jas.-Clk. PI. VII. figs. 70-74. 



I shall not describe this infusorian in the same systematic 

 manner that has been adopted in treating of previous genera, 

 because I do not know much about its internal organization ; 

 but in order that the direct alliance of the Flagellata with the 

 Ciliata may be illustrated in this memoir in its strongest light, 

 and inasmuch as Heteromastix is by far the best example of 

 such a transition between the two above-mentioned orders, 

 I shall take the liberty of quoting what I have already pub- 

 lished in regard to it in another place f. 



"Here is an infusorian (figs. 70-74), from fresh water. 



* erepos, dissimilar ; fxaa-ri^, a lash. This genus was origiually de- 

 scribed in my published volume of Lowell Lectures, ' Mind in Nature,' 

 p. 146, %. 88. t See note *. 



