GENERAL CHARACTERS 115 



probable that these are to be looked upon as vestigial or 

 rudimentary cilia, i.e., as the representatives of cilia which 

 were of the ordinary character in the ancestors of Stylo- 



u 







Ji.ci - 



FIG. 23. A, Stylonychia mytilus, ventral aspect, showing the buccal 

 groove (buc. gr.) and mouth (mth) t two nuclei (nu, mt), contractile 

 vacuole (c. vac), and cilia differentiated into hook-like (h. d), bristle- 

 like (b. ci), plate-like (/. ci), and fan-like (m. d) organs. 



B, one of the plate-like cilia of the same (/. d in A), showing its 

 frayed extremity. 



c, transverse section of Gastrostyla, an allied form to Stylonychia, 

 showing buccal groove (buc. gr.), small dorsal cilia (d. d), hook-like 

 cilium (h. d), and the various cilia of the buccal groove, including an 

 expanded fan-like organ (m. d). A and B after Claparede and Lach- 



mann ; C after Sterki. 



nychia, but which have undergone partial atrophy, or 

 diminution beyond the limits of usefulness, in correspond- 

 ence with the needs of an animalcule which has taken to 



I 2 



