183 



The mere modifications in the form and proportions of plates, even 

 though they result in the deTelopment or suppression of antapical horns, 

 is not, in my opinion, an adequate ground for generic distinctions among 

 the DinoflageUates. If applied to Ceratium hirundineUa, for example, 

 it would become necessary to erect new genera for the three, four and 

 five homed varieties or growth forms of this variable species ! The unity 

 of the genus Ceratium rests upon the well-defined character of the num- 

 ber of its plates and their relations. 



Berkeley, June 7, 1907. 



Papers Cited. 



1883—1887. Biitschli, 0., Protozoa. EL Abt. JIastigophora. Bronns Elassen 



n, Ord. Bd. 1. p. 617—1097. Taf. 39—55. 

 1834. Ekrenberg, C. C, Dritter Beitrag zur Erkenntniss groCer Organisation in 



der Bichtong des kleinsten Banmes. Abb. Egl. AJi:ad. d. Wiss. zu Berlin. 



1883. S. 145—336. 11 Tat 



1905. Entz, Gr. jr.. Beitrage zur Eenntnig der Peridineen. Matli.-naturwiss. Ber. 



au8 Ungam Bd. 20. p. 96—144. 6 Taf. 66 Fig. 

 1884. Elebs, G., Bin kleiner Beitrag zur Kenntnis der Peridineen. Bot. Zeit. 

 Bd. 42. S. 721—733, 737—745. Taf. 10. 



1895. Schiitt, F., Die Peridineen. Ergebn. d. Plancton-Expedition. Bd. IV Ma. 



Tefl. L 170 S. 27 Taf. 



1906. Peridiniales. Engler und Prantls Nat. Pflanzenfamilien. L Teil. 



Abt. b. S. 1—30. 43 Figg. 



1883. Stein, Fr., Der Organismus der Infosionstbiere. III. Abth. 11. Halfte. Die 

 Naturgeschichte der Arthrodelen FlageUaten. 30 S. 25 Taf. 



1896, Vanhoeffen, E., Das Genus Ceratium. Zool. Anz. Bd. 19. S. 133—134. 



