SYNGENETIOE. 



15 



vacuoles, and one to two band- or plate-like chromatophores with 

 a brown or yellow colour, and sometimes a pyrenoid. 



Reproduction takes place by vegetative division, or asexually by 

 zoospores, akinetes (or aplanospores ?). Sexual reproduction is un- 

 known. They are all fresh water forms. 



To this class may perhaps be assigned the recently arranged and very 

 little known orders of Calcocytaceec, Murracytacece, Xanthellacece, and 

 Dictyochacea, which partly occur in the 

 free condition in the sea, in the so-called 

 " Plankton," and partly symbiotic in 

 various lower marine animals. 



The Syngeneticce are closely re- 

 lated to certain forms in the animal 

 kingdom, as the Flagellatse. 



Order 1. Chrysomonadinaceae. In- 

 dividuals, uni- or multi-cellular, swim- 

 ming in free condition, naked or sur- 

 rounded by a mucilaginous covering. The 

 cells are generally oval or elongated, with 

 2 (rarely only 1) cilia, almost of the same 

 length, and generally with a red " eye-spot 

 only) band-shaped chromatophores. Keproduction by the longitudinal divi- 

 sion of the individual cells either during the swarming, or during a resting 

 stage ; in the multicellular forms also by the liberation of one or more cells, 

 which in the latter case are connected together. 



A. Unicellular : Chromulina, Cryptoglena, Microglena, Nephroselmis. 



B. Multicellular : Uroglena, Syncrypta (Fig. 11), Synura. 



Among the unicellular Chrysomonadinaceae are probably classed some forms 

 which are only stages in the development of the multicellular, or of other 

 Syiif/eneticce. 



Order 2. Chrysopyxaceae are unicellular, and differ mainly from the pre- 

 ceding in being attached either on a slime-thread (Stylo- 

 chrysalis), or enclosed in an envelope (Chrysopyxis, Fig. 

 12). They have two cilia, and multiply by longitudinal 

 (Chrysopyxis) or transverse division, and the swarming 

 of one of the daughter-individuals (zoospore). Division 

 may also take place in a motionless stage (palmella-stage). 



Order 3. Dinobryinaceae. The individuals are ori- 

 ginally attached, uni- or multi-cellular ; each individual 

 cell is distinctly contractile, and fixed at the bottom of a 

 cup-shaped, open envelope. Cilia 2, but of unequal 

 length. Asexual reproduction by zoospores, which are 

 formed by straight or oblique longitudinal division of 

 the mother-cell, during a palmella-stage which is pro- 

 duced in the winter aplanospores. Epipyxis, Dinobryon. 



FIG. 11. Syncrypta volvox : the multi- 

 cellular individual is surrounded by a 

 mucilaginous granular envelope. 



' at their base, and with 2 (rarely 1 



Fio. 12. Chrysopyxis 

 bipes : m envelope, EC 

 chromatophure, cv 

 contractile vacuole. 



