258 Prof. H. James-Clark on the Spongias ciliatge 



gella recall Anisonema (§ 13) most vividly to mind ; but, on 

 the other hand, the group of cilia {cl) in the obliquely longi- 

 tudinal furrow (/) in close proximity to, and evidently acting 

 more or less as allies with, the flagella {fl,Ji^), find their pa- 

 rallel in the "proboscis-like lash" (fig. 75,Ji) and vestibular 

 cilia {cl) in the oblique buccal furrow of Pleuronema (§ 16) 

 and Dysteria (§15). How closely allied the two latter are to 

 the former is not the immediate question here j it is, are they 

 related at all ? We think there can be no hesitation in reply- 

 ing in the affirmative ; but in order that the reader may have 

 the proof before his eyes, I think it will not be out of place, in 

 this memoir, to introduce some of the midoubted Ciliata which 

 possess at the same time organs that are as ti'uly flagellate in 

 character as are the flagella of Anisonema^ Astasia^ &c. The 

 genus Dysteria shall be om* first example. 



§ 15. Dysteria, Huxley. 

 Dysteria jprorcefrons J Jas.-Clk.* PL VII. figs. 77, 78. 



This species " is an infusorian between two leaves or flexible 

 shells {vyV^) of unequal width, which are united by a sort of 

 hinge along the left border, and gaping to a more than equal 

 extent along the right side, where the upper one {v) far over- 

 hangs the other (v^, hk) throughout the whole length of its free 

 edge. The broader or dorsal shell {v) is convex towards the 

 eye, and the whole organization lies within its concavity, 

 whilst the narrower one (5/c, v^) is flat, simply covering the 

 body, and as a natural consequence does not include any part 

 of it. The open space between them is endowed with a row 

 of closely set, large vibratile cilia {cl), which differ in size ac- 

 cording to their position, those in front being by far the longest, 

 and those along the side scarcely more than half as long ; and, 

 in addition, there is one {fl) which, from its great size, has 

 more of the character of a proboscis or prehensory flagellum, 

 and is attached nearly at the extreme anterior border of the 

 row {cl). 



" It is not an easy matter in this case to determine how much 

 of the one-sided, cilia-bordered furrow corresponds to the disk 

 or vestibule of Epistylis, Stentovy Paramecium, or Pleuronema', 

 nor does it affect the question of the degree of obliquity of the 

 conformation of this animal, so long as we see that, whatever 

 it may be, either wholly or in part a vestibule, it is at least 

 extremely oblique, and that it is not possible to view it from 

 any point but that the body appears asymmetrical in relation 

 to it. 



* See 'Mind in Nature/ ut supr. p. 171, fig. 100. 



