EXPLANATION OF PLATE XXX. 

 FIG. 



1-4. STENTOR IGNEUS, Ehr. i, Attached, fully extended animalcule, x 70 ; 2 and 3, 

 free-swimming conditions ; 4, embryo released by the disintegration of the 

 parent zooid. 



5. STENTOR PEDICULATUS, From., x 250 (De Fromentel). 

 6, 7. STENTOR AURICULA, S. K., ventral and dorsal aspects, x 120. 

 8, 9. STENTOR MULTIFORMIS, Stein, x 200 (Stein). 



10-20. STENTOR POLYMORPHUS, Miiller sp. 10, Attached, fully extended animalcule, 

 x 120; II, a social colony, colourless variety, attached to a rootlet of 

 Anacharis, which has built up through excretion a common mucilaginous 

 basis, x 15; 12, examples conjugating with their neighbours, as delineated 

 by Balbiani ; 13, free-swimming zooid with attenuated posterior region; 

 14, example with, at/r, a laterally developed membranous crest, representing 

 the initial condition of the peristomal ciliary circlet of a future zooid 

 (Ehrenberg) ; 15, an encysted example (Stein); 16, an animalcule dis- 

 charging faecal matter, as observed by the author; 17 and 18, groups of the 

 green variety, natural size, and x 50, after Ehrenberg; 19 and 20, portion 

 of the nucleus or endoplast, showing in the former instance the union of the 

 component granular nodules by an interconnecting cord or funiculus ; at 20 an 

 isolated nodule with an enclosed elongate vacuolar structure, x 300 (Stein). 



21. STENTOR BARETTII, Barrett. Fully extended animalcule, x 100. 



22-23. STENTOR ROESELII, Ehr. 22, Fully extended example affixed within its excreted 

 mucilaginous sheath, x 80 ; at pr, initial condition of a second peristome 

 (Clap. & Lach.) ; 23, basal or pedal region with pseudopodic peripheral 

 extensions (after Simroth) ; 24, clavate free-swimming zooid with at pr 

 secondary peristome in progress of development (Stein); 25, more advanced 

 condition of fissure, the second peristome, pr, having attained a contour and 

 proportions that correspond closely with those of the primary one (Clap, 

 and Lach.) ; 26, last phase of fissive process, the anterior moiety being 

 now almost completely separated from the posterior one (from a MS. 

 drawing by H. E. Forrest); 27-30, progressive developmental phases, after 

 Claparede and Lachmann ; 31, supposed germ-sphere as delineated by Stein ; 

 32, foot or basal region with tuft of longer setose cilia, after Stein ; 33, free- 

 swimming semi-contracted animalcule (Stein). 



