EXPLANATION OF PLATE IV. 



Fig. 



1-5. CODOSIGA UMBELLATA, Tatem sp,, vol. i. p. 335. — 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 funda- 

 mental formula ; 4, an example with the pedicle quadripartitely branched 

 (Tatem) ; 5, an abnormal type with five primary subdivisions of the 

 supporting pedicle (Stein). 



6-10. CODOSIGA (Epistylis) botrytis, Ehr. sp. (Stein), vol. i. p. 334. — 6, An ab- 

 normally 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 larger zooid is dividing by longitudinal fission, the group of 

 four smaller ones at i> having been derived from similarly 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., vol. i. p. 357, x 1250. 



12. Monosiga Steinii, S. K., vol. i. p. 331. — Five zooids attached to a stalk of 



Vorticella convallaria, x 650 (Stein). 



13-16. Salpingceca convallaria, Stein (Stein), vol. i. p. 357. — 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., vol. i. p. 331. — A social group, x 1800. 



18. Monosiga longicollis, S. K., vol. i, p. 333, x 1800. 



19-21. Monosiga consociata, S. K., vol. i. p. 330. — 19, A group showing at a 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 zooid, with collar and flagellum withdrawn, about to enter upon an encysted 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 1500; 20 

 and 21, zooids with collars and flagella retracted and assuming a vacuolar 

 amoeboid phase. 



