EXPLANATION OF PLATE XXX. 



Fig. 



1-4. Stentor IGNEUS, Ehn, vol. ii. p. 594. — I, Attached, fully extended animalcule, 

 X 70 ; 2 and 3,. free-swimming conditions ; 4, embryo released by the dis- 

 integration of the parent zooid. 



5. Stentor pediculatus, From., vol. ii. p. 596, x 250 (De Fromentel). 



6, 7. Stentor auricula, S. K., vol. ii. p. 595, ventral and dorsal aspects, x 120. 



8, 9. Stentor multiformis, Stein, vol. ii. p. 595, x 200 (Stein). 



10-20. Stentor polymorphus, Miiller sp., vol. ii. p. 590. — 10, Attached, fully extended 

 animalcule, x 120 ; 11, a social colony, colourless variety, attached to a rootlet 

 of A uac/iaris, 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 Barretti, Barrett, vol. ii. p. 593.— Fully extended animalcule, x 100. 



22-33. Stentor Roeselii, Ehr., vol. ii. p. 591. — 22, Fully extended example affixed 

 within its excreted mucilaginous sheath, x 80 ; at ^r, initial condition of a 

 second peristome (Clap. & Lach.) ; 23, basal or pedal region with pseudo- 

 podic peripheral extensions (after Simroth) ; 24, clavate free-swimming zooid 

 with at /r secondary peristome in progress of development (Stein); 25, more 

 advanced condition of fissure, the second peristome, /r, 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 ciha, after Stein ; 33, free- 

 swimming semi-contracted animalcule (Stein). 



