50 



THE INVERTEBRATA 



Of all the Mastlgophora, the members of this order most closely 

 resemble the typical plants. 



Chlamydomonas (Figs. 23, 25). Typical solitary members of the 

 order, with two flagella; an eye-spot; a close-fitting cellulose cuticle; 

 and one pyrenoid. The various species exhibit isogamy, anisogamy, 

 and intermediate conditions (see p. 26). In fresh waters. 



Polytoma (Fig. 24). A colourless Chlamydomonas', retaining the 

 eye-spot (usually) and the habit of starch formation ; but with the 



t-ann. 



11 tc- 



Fig. 40. Dinoflagellata. A, Ceratium macroceras, x about 300. B, Polykrikos 

 schwarzt, x 250. C, A discharged "nematocyst" oi Polykrikos. After various 

 authors, with modifications, ann. annuli; cph. chromatophore ; cu. cuticle; 

 In.fl. longitudinal flagellum ; rite. " nematocyst" ; nu. nucleus ; sul. sulcus ; sut. 

 suture between plates of cuticle ; tr.fl. transverse flagellum. 



cuticle composed of some substance which does not give the cellulose 

 reaction. Nutrition saprophytic by means of simple substances (fatty 

 acids, amino acids, etc.). Syngamy is facultatively hologamy or 

 merogamy, isogamous or anisogamous, according to the age of the 

 gametes. In infusions of decaying animal substances. 



Carteria (Figs. 35, 36). Differs from Chlamydomonas in having four 

 flagella. It is probably a species of this genus that is symbiotic in the 

 turbellarian Convoluta roscoffensis . 



Haematococcus (= Sphaerella, Fig. 42). Differs from Chlamy- 



