430 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Glenodinium compressa, n. sp. Fig. 21, a, b, c. 
This species resembles G. acuminata of Ehrenberg except that it is strongly compressed laterally. 
The longitudinal furrow extends nearly to the extremity of the animal. It begins as a narrow slit and 
widens as it progresses upon the left side; it also becomes 
much deeper on this side and at the bottom of the depres- 
sion the longitudinal flagellum is inserted. The transverse 
furrow runs evenly around the body near the upper pole, 
giving to the shell almost the aspect of an Amphidinium. 
Brown chromatophores may or may not be arranged radi- 
ally about a central amylum granule. One striking char- 
acteristic is the depth of the two furrows. The nucleus 
is elongate and somewhat curved; it lies against the 
posterior wall of the rather thick shell. Not uncommon. 
Length 40, w; breadth 32//; width 18//. 
The posterior end of the animal is often somewhat 
pointed and this point frequently becomes attached, so 
that the animal whirls around upon it as upon a pivot. 
Glenodinium cinctum Ehr. Fig. 22. 
The body is globular, smooth, and homogeneous. 
Brown chromatophores arranged radially, each in the form 
of a cone, the base of which rests against the shell while 
the points turn inward. A bright-red eye-spot may or may 
not be present; when present it is placed near the junction 
of the two furrows. The longitudinal furrow is small. 
Fresh water and salt. 
Length and diameter the same, 21//. 
This species was observed by Peck ’93. 
Fig. 21.— Ventral anti dorsal aspects of Pcridinium divergcns. 
Genus PERIDINIUM Ehr. ’32, Stein ’83. 
(Claparede & Lachmann ’58; Bergh '81: Pouchet '83; '85; Gourret ’88; Biitschli ’86.) 
The form is globular, ovoid or elongate, the apex frequently drawn out into a long tube. The 
transverse and longitudinal furrows are quite distinct, the former having often a spiral course about 
