KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 119 



The cji:oplasm is colorless, with a peripheral layer of stout rhabdosomes, 0.3 trausdiameter in 

 length. The nucleus lies in the lower epicone. It is an ellipsoid, 0.66 trausdiameter in length 

 and 0.50 in width, with about twelve moniliform chromatin tlin>ad.s on one face and a central 

 nucleolus. 



Binary fission is slightly oblitjue and the daughter cells form in chains as in other 

 dinoflagellates. 



DniEXSioxs.— Length, 22-32/^, rarely 10-37/^; transdiameter, 15-20f. 



OcciJRREXCE. — This species was originally described by Dujardin (1841) in 

 salt water from the ^lediterranean containing UJva which had stood for some 

 months. In fact most of the stndies of this interesting and perplexing flagellate 

 have been made from aquarium cultures. The only reports of the occurrence 

 of the species from marine waters are those of Saville-Kent (1880-82), who 

 found it in water samples from St. Heliers, Jersey, as well as in aquarium 

 cultures from this region; of Cienkowsky (1881), who reported it from the 

 White Sea; of Gruber (1884), who listed it from the harbor at Genoa, Italy; 

 of Gourret and Roeser (1886), who found it sparingly in harbor water at 

 ]\Iarseilles, France; of Massart, who collected it on brackish-water pools at 

 Palingbrug. near Nieuport, Belgium; of Entz (1897), who discovered it in col- 

 lections from brackish-water pools on a coral islet at Tengeriek, New Guinea ; 

 of Lohmann (1909), who records it from the harbor waters at Kiel ; and Lebour 

 (1917o, h), who found it sparingly in water samples at Phnnouth, England. 



On the other hand, it has been reported in great abundance in sea water 

 aquaria at Frankfort, Germany, by Fresenius, who called it GJyphidinm. 

 marinum. It was again found by Cohn (1865), who gave it this same name, in 

 a window aquariimi at Breslau supplied from Helgoland. Blochmann's (1884) 

 studies were made on material from the Heidelberg Aquarium; Senn (1909) 

 at Basel, Switzerland, noted it in great abundance in a culture from Xai)les 

 containing Bri/opsis, kept at 20° to 25° and not fouled by bacteria, flagellates, 

 and ciliates. Griessmann noted its occurrence in aquaria supplied with sea 

 water and seaweeds from Roseoff, Helgoland, and Yillefranche. Lebour 

 (1917&) reports it in great abundance in laboratory plankton cultures, especially 

 with the diatom A^ifzschin closfcrium. 



Of special interest is its occurrence in continental salt lakes of the pro^dnce 

 of Kharkoff, Russia, reported by Stepanotf (1885). 



Synonymy. — There is no doubt that the organism described by Fresenius 

 (1865) as Ghjphiclium marinnm, and later reported by Cohn (1886), is Dujar- 

 din's OxijrrJiis mitrinn. The peculiar location of the flagella and their ])osterior 

 position in locomotion, coupled with Dujardin's (1841) noncommittal horizontal 

 orientation of his figures, misled these earlier investigators in their conclusions. 



