EXPLANATION OF PLATE XVIII. 

 FIG. 



i-io. ANTHOPHYSA VEGETANS, Miill., vol. i. p. 267 (Stein). i, Prolific colony-stock, 

 with lax homogeneously-granulate branching stem, x 500 ; 2, detached 

 monad cluster, or " coenobium," seen from below ; 3, ccenobium, showing its 

 relationship to supporting pedicle, as seen in vertical optic section, x 1000 ; 

 4 and 5, free-swimming coenobia, composed of a small number of monads 

 only ; 6, disintegrated ccenobium, the monads with tail-like posterior pro- 

 longations, x 1000 ; 7 and 8, independently motile monads, with pseudopodic 

 processes, derived from breaking up of the adult ccenobium ; 9, one such 

 motile zooid, fixed by a posterior pseudopod-like extension ; 10, early con- 

 dition of sedentary colony-stock, bearing a single ccenobium of eight 

 monads only. 



ir, 12. CLADOMONAS FRUTICULOSA, vol. i. p. 284 (Stein). 1 1, Adult tubular colony-stock 

 or zoothecium, showing at a a detached monad, and at b two monads, the 

 result of longitudinal fission, temporarily inhabiting the same tube, x 650 ; 

 12, terminal branchlet of variety having dark-coloured band-like internodes. 



13-19. BlCOSCECA LACUSTRIS, vol. i. p. 275, J.-Clk. 13, Adult monad in lorica, x 1250 ; 

 14 and 15, successive phases of transverse fission; 16, distally separated, 

 free-swimming integer of fissive process, presenting a Heteromita-like 

 aspect ; 17, monad with spirally-coiled flagella, retracted within its lorica ; 

 1 8, lorica with sporular contents ; 19, adult monad in lateral aspect, showing 

 eccentric development of thread-like footstalk, and lip-like prolongation of 

 the anterior region, x 1250. 



20. BlCOSCECA CURVIPES, S. K. Contained monad dividing by longitudinal fission 

 or conjugating with an externally derived zooid, x 1500. 



21, 22. BlCOSCECA GRACILLIPES, J.-Clk., vol. i. p. 276. 21, normal form ; 22, example 

 with shorter pedicle and more exsert zooid, x 1250. 



23. BICOSCECA TENUIS, S. K., vol. i. p. 276, x 1500. 



24. HEDRJEOPHYSA BULLA, S. K., vol. i. p. 274, x 1500. 



25-29. BlCOSCECA POCILUJM, S. K., vol. i. p. 277. 25, Typical adult form, x 1000 ; 26, 

 monad dividing by transverse fission ; 27 and 28, obtusely and acuminately 

 pointed free-swimming monads derived from the fissive process ; 29, a 

 similarly derived monad adherent by its posterior extremity, but as yet 

 wanting the characteristic protective lorica. 



30, 31. DIPLOMITA SOCIALIS, S, K., vol. i. p. 289. 30, Social group attached to a 

 confervoid filament ,-31, two monads within their stalked loricae, x 1500, 

 at e eye-like pigment-spots. 

 32. STYLOBRYON EPISTYLOIDES, S. K., vol. i. p. 279, x 1 500. 



33-35- CEPHALOTHAMNIUM CJESPITOSA, S. K., vol. i. p. 272 (Stein). 33, Adult colony- 

 stock, x 1000 ; 34 and 35, free-swimming and attached isolated monads. 



