166 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



may be formed in succession, the o\;ter usually large, as a result of distention, 

 the inner following the contour of the body very closely (pi. 5, fig. 53). This 

 inner membrane forms as a thin pellicle on the outer surface of the body and 

 is expanded by incoming fluid. 



Distribution^. — The occurrence of Gijunwdiiiiiiin has l)een recorded mainly 

 from waters of temperate latitudes. Two species only, G. wilczeki and G. 

 pseudonodiluca, were found by Pouchet in scant numbers in the Arctic Ocean 

 near Spitzbergen, July 31, 1892. One marine species has been recorded from 

 the tropics, G. fusiis, by Karsten (1907) in the Indian Ocean at 2° 58' 5 X, 

 46° 50' 8 E. Klebs (1912) found three fresh-water species near Buitenzorg, 

 Java, G. aeruginostim, G. iorgoriense, and G. varians. 



Of the remainder, twenty are fresh-water forms. Of these the greater 

 number of species have been found in Switzerland as the result of the work of 

 the Swiss naturalist Peuard. The following species are recorded from Lake 

 Geneva : G. helveticum, G. viride, and G. rufescens (G. uberrimum) by Penard 

 (1891), G. palnstre by Guyer (1910) ; and from other waters in Switzerland, 

 G. carinatnm, G. fuscum, and G. parndoxum by Schilling (1891a), and G. aern- 

 ginosum by Amberg (1900). The lakes and ponds in Germany have also proved 

 a fertile field, particularly the Lake Plon region. The species recorded here 

 are: G. parado.rinu by Lenmiermann (1903(/) ; G. helveticwn and G. tenuis- 

 simum by Lauterboru (1894, 1910) ; G. palustre by Schilling (1891^) ; G. fuscio)) 

 by Ap.stein (1896) and others; G. zacliariasi by Zacharias (1899); G. rotun- 

 datum by Klebs (1912); and G. aeruginosum by Marsson (1901). Allman 

 (1854, 1855) reported G. uherrimum (as Peridinium ttberrima) from Dublin, 

 Ireland. West and "West (1909o) found G. paradoxum in both the English 

 and Scottish lakes and G. zachariasi in the Irish lakes. From Austria-Hungary 

 Entz (1910) has recorded G. zachariasi and Stein (1878) G. votiiccJJa and G. 

 aeruginosum. The latter species has also been recorded from the Finnish lakes, 

 with G. fuscum, by Levander (18947;, 1900). Gymnodiniurn fuscum was noted 

 in the Zealand and Jutland lakes in Demnark by Weseuberg-Lund (1904) and 

 in Brazil by Cunha (1913), who also recorded G. viride from the same place. 

 Butschinsky (1897) records G. aenigi)iosniti from Odessa, Russia, and Bolo- 

 chonzew (1903) G. palustre from the Volga River. A single record comes from 

 ISTew Zealand of G. varians by ^Slaskell (1887) and one of G. hiciliatum from 

 Japan by Ohno (1911). The species G. musei was noted at Paris, France, by 

 Pouchet" (1887). 



Of these fresh-water species G. fuscum and G. aeruginosum are the most 

 widely distributed. Unfortunately the location of the discovery of G. fuscum 

 in Brazil has not been given by Cunha (1913), so that no deductions can be 

 made in regard to its temperature relations. 



Of the twenty marine species the larger number come from the Mediter- 

 ranean and the Atlantic. These are G. cucumis, G. diploconus, G. fusus, G. 

 gleha, G. rhomljoides, and G. vestifica, described by Schiitt (1895). L^nfortu- 



