28 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 30 Ser. 



Summary of Characteristics. 



1. Backward swimming, with no indication of a ''Mund- 

 naht". 



2. Peristomal spire consisting of two rows of cilia united 

 at the ends and including the terminal mouth within the 

 inner end of the spire. 



3. Apparent atrophy of the mouth and peristomal spire 

 as a prophase of division, and differentiation of the same for 

 each daughter animal as a telophase. 



4. Peculiar disposition of the chromatin granules at rest 

 and in division, and non-staining homogeneous nucleolar 

 masses of unknown function. 



5. Constant aboral position of the micronucleus at a 

 distance from the macronucleus in resting stages. 



6. Apparent mitotic division of the micronucleus as the 

 initiative of cell division. 



7. Polar position of the micronucleus during macronu- 

 clear division. 



8. Division by lateral or oblique fission. 

 Conjugation has not yet been observed in either Licno- 



phora niacfarlandi or Boveria suhcylindrica. 



Relation of These Infusoria to Their Host and to 



Each Other. 



Ordinarily there is no apparent relation between the two 

 forms. So far as can be seen through the wall of the liv- 

 ing respiratory tree, both are usually attached to the mem- 

 brane, feeding busily and quite independently. Similar 

 food masses are found in each, — diatoms and leucocyte- 

 like or epithelium cells. In several holothurians, however, 

 where the number of both forms was very great, many of 

 the Licnophorce had been feeding upon the BovericB. In 

 serial sections from this material, several cases were found 

 in which, as in fig. 10, an individual of Boveria snbcy- 

 lindrica is held within the pharynx of a Licnophora^ and 

 others in which a Boveria occurs as a rounded food mass 



