EXPLANATION OF PLATE IV. 



FIG. 



1-5. CoDOSIGA UMBELLATA, Tatem sp. i, More normal and adult colony-stock 

 with compound pedicle or zoodendrium, tripartitely branched, x 625 ; 2, a 

 single zooid, X 1250; 3, a simpler growth of the same fundamental formula; 

 4, an example with the pedicle quadripartitely branched (Tatem) ; 5, an ab- 

 normal type with five primary subdivisions of the supporting pedicle (Stein). 

 6-10. CODOSIGA (EPISTYLIS) BOTRYTIS, Ehr. sp. (Stein). 6, An abnormally luxuriant 

 colony with a spheroidal cluster of associated zooids, at a one of the latter 

 detached from the parent stock, x 650 ; 7, a colony-stock in which at a a 

 larger zooid is dividing by longitudinal fission, the group of four smaller ones 

 at b having been derived from similar repeated subdivision of an original 

 single zooid ; 8, a free-swimming zooid detached from a sedentary colony ; 

 9, coalescence or conjugation of a similar free swimming zooid with a normal 

 sedentary form ; 10, a zooid emitting minute pseudopodic processes which 

 present the aspect of adherent Bacteria. 



11. SALPINGCECA CAMPANULA, S. K., x 1250. 



12. MONOSIGA STEINII, S. K. Five zooids attached to a stalk of Vorticella con- 



vallaria, x 650 (Stein). 



13-16. SALPINGCECA CONVALLARIA, Stein (Stein). 13, Three normal zooids attached to 

 stem of an Epistylis, x 650 ; 14, a zooid dividing by longitudinal fission ; 

 15, zooid with lorica of an irregular and abnormal form; 16, a detached 

 and free-swimming zooid. 



17. MONOSIGA FUSIFORMIS, S. K. A social group, x 1800. 



1 8. MONOSIGA LONGICOLLIS, S. K., x 1800. 



19-21. MONOSIGA SOCIALIS, S. K. 19, A group showing at a zooid with collar and 

 flagellum withdrawn about to enter upon an encysted state, and to the 

 extreme right an example with a short pedicle, x I5o> 2O and 21, zooids 

 with collars and flagella retracted and assuming a vacuolar amoeboid phase. 



