EXPLANATION OF PLATE XVIIL 



Fig. 



i-io. Anthophysa vegetans, Rliill., 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 ; g, 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. 



II, 12. Cladomonas fruticulosa, vol. i. p. 284 (Stein).— 11, 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 ; 

 1 2, terminal branchlet of variety having dark-coloured band-like internodes. 



13-19. BiCOSCECA 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 flagcUa, retracted within its lorica ; 

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

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

 the anterior region, x 1 250. 



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

 or conjugating with an externally derived zooid, x 1500. 



21, 22. BiCOSCECA 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 1 500. 



24. HEDR.EOPHYSA BULLA, S. K., vol. i. p. 274, X I50O. 



25-29. BiCOSCECA POCILLUM, 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. DiPLOMlTA SOCIALIS, S. K., vol. i. p. 2S9. — 30, Social group attached to a 

 confervoid filament ; 31, two monads within their stalked loricee, x 1500, 

 at e eye-like pigment-spots. 



32. Stylobryon epistyloides, S. K., vol. i. p. 279, X 1500. 

 33-35. Cephalothamnium c^SPITOSA, S. K., vol. i. p. 272 (Stein). — 33, Adult colony- 

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



