THP] AMERICAN MONTHLY 



[January, 



the jelly-mass. The expanded body 

 extends beyond this mass, when 

 fully contracted it is drawn down 

 into it. The extended body of the 

 species under consideration is elong- 

 ated, tapers gradually from its point 

 of greatest diameter, which is in the 



inferior third of the body, to a 

 small, rounded, inferior extremity. 

 Above the dilated portion, the 

 diameter, after diminishing for a 

 short distance, becomes uniform 

 almost up to the mouth, where it 

 expands slightly. Peristome 



^- 



EXPLANATION OF THE FIGURES. 



Fig. I. The animal attached and ex- 

 tended, a, Endoplast. b. Contractile 

 vesicle, c, Chlorophyll granules, most 

 apparent in the dilated portion of the 

 body, d, " Fusiform body." e, (Eso- 

 phagus. /, Anus, g, Disc, //, Peris- 

 tome with cilia (^), /, Transverse 

 striae, k, Point of attachment to stalk 

 (/.). m, Division of stalk. ;/, Stalk re- 

 maining after detachment of animal. 



Fig. 2. Animal partially contracted ; 

 peristome and disc inverted ; the letters 

 refer to the same parts as in Fig. i (except 

 o which refers to the inverted extremity.) 



Fig. 3. Animal more contracted, and 

 attached. Lettered as above, with addi- 

 tion of p the posterior circlet of cilia. 



Fig. 4. One of the free individuals, very 

 recently detached. 



Fig. 5. The stage in which the free 

 individual has become attached by the 

 extremity which was formerly joined to 

 the stalk at q. The peristome and disc 

 are again everted ; the process of this 

 latter change is carried on very slowly. 

 The condition here represented is at- 

 tained about forty-eight hours after the 

 free state is assumed. 



