UNIVERSITY OF CALIFORNIA PUBLICATIONS 
ZOOLOGY 
Vol. 2, No. 8, pp. 341-368, Pls. 17-19 January 6, 1906 
CONTRIBUTIONS FROM THE LABORATORY 
OF THE 
MARINE BIOLOGICAL ASSOCIATION OF SAN DIEGO. 
Vili. 
DINOFLAGELLATA OF THE SAN DIEGO 
REGION.—I. ON HETERODINIUM, A 
NEW GENUS OF THE PERIDINIDAE 
BY 
CHARLES ATWOOD KOFOID. 
The investigations of the plankton of the Pacific at the San 
Diego Station during the past three years has brought to heht 
a number of species belonging to the family Peridinidae which 
do not conform to any known genus. They all present in com- 
mon a number of characters which eall for the establishment of 
a new genus for the reception of the several species represented. 
To this genus also belong seven species described by Murray 
and Whitting (799) from the tropical Atlantic as members of 
the genus Peridinum to wit: Peridinium hindmarchu, P. milneri, 
P. blackmant, P. leiorhynchum, P. trirostre, P. tripos, and P. 
doma. Gonyaulax triacantha Jorg. is also to be referred to this 
genus. All of these species except P. trirostre and Gonyaulax 
triacantha have been seen by me and a fuller discussion of their 
structure will appear elsewhere. In the following pages the brief 
discussion of each is based upon Murray and Whitting’s figures. 
I am indebted to Miss E. J. Rigden, assistant in the summer 
of 1904 at the San Diego Marine Biological Station, for some of 
the sketches utilized in the plates accompanying this paper and 
also for the skill and thoroughness of her examination of the 
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