130 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



The species found by us on the Pacific coast were taken in July and August. 

 Ph^ukton hauls have been made throughout the year, hut preservative has been 

 immediately added to these hauls, and it is very rarely indeed that these soft, 

 naked forms preserve their identity after contact with the fixing fluid. 



Historical Discussion 



The genus Am pliidinium was established by Claparede and Lachmann 

 (1858-61), who figured ^1. operculatiun and two other forms which they thought 

 might be varieties of the same species. These were later established by Diesing 

 (1866) as A. opcrculatum var. discoidalis and A. operculatum var. emarginata. 

 Their allocation, however, in this genus is doubtful, at least until they have 

 been found again. Stein (1883) figured as A. operculatum a form which Leni- 

 mermann (1900) changed to var. steini. Klebs (1884) also figured as A. oper- 

 culatum what we have designated as A. Mehsi, nom. sp. nov. Using the same 

 species name, Herdman (1911-13) figures still another form which seems to 

 be specifically different from the three previously described under that name. 

 This we have designated A. herdmani nom. sp. nov. 



In 1888 Daday added to the genus A. aculeatum as a new species, a form 

 which has no apj^arent Amphidinium characteristics, if indeed it belongs in the 

 Dinoflagellata at all, which seems doubtful. Schroder (1911) uses the same 

 species name for a totally different form and one which also presents no 

 Am pliidinium characteristics. These two forms we exclude from the genus. 

 Schroder, in the same monograph, adds A. glohosum and A. lauceolatum. The 

 first of these is without Am pliidinium characters and must likewise be excluded 

 from the genus. A. lanceolatum we regard as an Amphidinium, but one which 

 needs to be redescribed. 



Stein (1883) described the only fresh- water form in the genus, A. lacustre. 



Lemmermann (1900) added to the genus as A. ovoideum a form previously 

 described by huuself (1896) as Proroccntrum niicans. Lohmann (1908) added 

 the incompletely described species A. crassum, A. longum, and A. rotundatum. 

 A. sulcatum was added by Kofoid (1907). 



To the eight previously described species, to wit, A. crassum, Lohmann, A. 

 lacustre Stein, A. longum Lohmann, A. opcrculatum Claparede and Laclmiann 

 emend., A. ovoideum Leuuuermann, A. rotundatum Lohmann, A. steini (Stein), 

 and A. sulcatum Kofoid, we add twelve new species from the plankton and 

 beach of the Pacific off La Jolla, California, as follows: A. asymmetricimi, 

 A. corpulentum, A. ciicurhitella, A. cucurhita, A. dentatum, A. fastigium, A. 

 galhanum. A. pacificum, A. scissum, A. truncatum, A. turho. and ^1. vasculum, 

 and two more from the literature, A. herdmani nom. sp. nov. and A. klehsi nom. 

 sp. nov., based on Herdman 's (1911-1913) and Ivlebs's (1881) figures of A. 

 operculatiun , respectively. 



