278 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



color places them near the red end of the spectrum, a fact which links them 

 with the further evolution of the G^^^unodinioidae in the more highly specialized 

 Coclilodinium, and in Poxchetia, and Eri/fhropsis. 



The species of this genus are, most of them, holozoic in nutrition. Four 

 species onlv possess chromatophores, G. melo sp. nov., G. falcatum sp. nov., 

 G. pnsiUum (Schilling), and G. foliaceum sp. nov. Of these G. melo and G. 

 foJiacenm show undouhted evidences of holozoic nutrition, such as the presence 

 of food masses and vacuoles, products of metaholism, in the cytoplasm. The 

 same conditon holds true in other G^innodiniidae, as in Ampliidiuiinn scissum, 

 A. corpulenium, Gymnodinmm agile, G. favuw, and G. herhacenm. Of the 

 remaining species most of them show evidences of holozoic nutrition, such as 

 food balls, oil glolndes, vacuoles, and refractive granules in the cytoplasm, the 

 accumulated products of metabolism or indications of periodic feeding and 

 digestion. 



Encystment is probably in many cases due to the ingestion of large food 

 masses and follows upon it, the cyst being formed to meet the needs of the 

 organism for a quiet period for its digestion. As the cyst wall is first foiined 

 it closely invests the body, becoming expanded at a later stage \\ii\\ the accumu- 

 lation of fluid within it by osmosis. In many cases of encysted indi%T.duals, those 

 enclosed in apparently newly formed cysts usually show the presence of food 

 bodies as in G. truncnfum (pi. 1, fig. 3), while others, in which the cyst has 

 become greatly enlarged, may be entirely free from food bodies, as are indi- 

 viduals just emerging from the cyst. 



Distribution 



Gyrodinium, like Gipinwdiuium, is widely distributed, but is found princi- 

 pally within the warm temperate waters. Two species only have thus far been 

 described from fresh water, G. hi/nliuum (Schilling) and G. pMsiUnm (Schil- 

 ling) near Basel, Switzerland (Schilling, 1891) ; the former species is also 

 recorded from the Danish lakes by Wesenberg-Lund (1901:). Of the remaining 

 twenty-three species three have been found within Arctic waters, G. grave 

 (Meunier), and G. lacliri/nia (Meunier) by Meunier (1910) near Nova Zembla, 

 and G. crassitm (Pouchet) by Pouchet (1894) near Spitzenbergeu. One species, 

 G. spirale (Bergh), has been recorded from the Indian Ocean by Karsten (1907). 

 The remainder are inhabitants of the warm and cool temperate waters. The 

 larger number of these come either from the Atlantic or the Bay of Naples, the 

 localities from which Schiitt's (1895) species were obtained. Tliese are G. 

 acutiim,. G. contortum, G. foliaceum, G. ohtusum, G. ovum, G. parvulum, G. pepo, 

 G. pingue, G. mitra, all figured and described by Schiitt as in the genus Gijmno- 

 dinitim, and the following species described by Pouchet: in 1883, G. fissum; in 

 1885fl, G. crassiim, G. enneatum (as Gymuodiiiinm gracile), and in 1885&. G. 

 spirale, all as in the genus Gymnodiniam. From the ^[editerranean at Cett€ 

 Pa-sillard (1905) I'QQOvdnG.crassum (Pouchet), Gourret (1883) from Marseilles 



