as a Craspedote Flagellate Infusorian. 77 



foration, and not a clear spot, may be demonstrated by bring- 

 ing a chamber into profile, so that its aperture (fig. 4, i) lies 

 on the extreme border ; for then an actual break in the con- 

 tinuity of the investing membrane becomes evident. 



Entering this aperture, we do not meet with any obstacle 

 for a little distance around it ; there is a clear open space 

 (fig. 4) ; but pressing onward beyond that, either to the right 

 or the left or directly forward, the cavity appears filled by a 

 collection of vibrating bodies. They seem to be arranged radi- 

 atingly from and about the centre. Close inspection, however, 

 modifies this view, and it turns out that they are based upon 

 the periphery of the chamber, and converge towards its centre, 

 where is a small unoccupied space. We presently recognize 

 these converging bodies to be craspedote flagellate monads (/) , 

 so closely packed together, side by side, as to form a continuous 

 stratum (figs. 2 and 4) over the whole concave face of the cham- 

 ber, excepting immediately about the aperture. Every feature 

 of the monad is strongly marked ; even the cylindrical collar is 

 so heavy and conspicuous that its outlines may be seen with as 

 low a power as two hundred diameters. We have studied 

 these bodies with a g-inch objective, and found it not at all 

 difficult to focus down upon the details of their organization 

 without pressing upon or even touching the specimen. 



These monads are in every general essential identical with 

 those which we originally found in Leucosolenia^ and like those 

 also recently described by Carter (Ann. & Mag. Nat. Hist., July 

 1871) in Grantia compressa. They are attached to the concave 

 face of the chamber by their posterior end (fig. 4, j) ; and the 

 anterior extremity, with its flagellum (fig. 3, I) and collar {k), 

 projects freely into the open space, and toward the centre of 

 the apartment. When fully expanded, the length of the body 

 and collar together is about one third, or a little more, of the 

 diameter of the chamber, so that nearly one third of the latter 

 is unoccupied at the centre, except by the tips of the flagella 

 converging from every direction. As the monads lie touching 

 each other on every side (fig. 2), they mutually flatten their 

 bodies, sometimes so much so as to give them a strong polygonal 

 outline ; or, when the whole mass is expanded, they scarcely 

 impress each other, and therefore retain a rounded contour. 

 By plunging the focus so as to look into the aperture of a cham- 

 ber, down upon the monads at the bottom (fig. 2) of it, an end 

 view of each cephalid is obtained. From this point the fore- 

 shortened cylindrical collar looks like a strong dark circle (fig. 

 3^, ^•), which retains its conspicuousness as we plunge down 

 further, even to the base, where it is attached to the body {j). 

 The outline of the latter is considerablv without the " dark 



