KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 459 



eminence at the antapex. The antapical region is grooved ventrally by tlie sulcus, which forms 

 a deep trough, to the right of which the liypocone swells out to a broad, slightly rounded lobe, 

 asymmetrically placed at the right of the shallow sulcal notch in the postmargin. 



The girdle at its jtroximal end is distant 0.06 of the total length of the body from the apex. 

 It curves arouud dorsally in a horizontal semicircle before beginning its posterior direction in 

 a steep descending left spiral 60° from the horizontal. It makes two complete turns around the 

 body and joins the sulcus distally 0.1 of the length of the body from the apex, flattening the 

 spiral again to the horizontal gradually in the last 0.75 turn. Its disi)lacenient thus equals 0.84 

 of the length of the body. The furrow is deeply impressed and is 0.1 transdiameter in width. 

 The anterior flagellar pore opens at the junction of the girdle and sulcus. The transverse 

 flagellum traverses one-half the entire length of the girdle. The posterior flagellar pore is 

 found at the distal junction of the sulcus and the girdle. Both pores open on the ventral face. 



The sulcus invades the epicone half tlie short distance to the apex. It makes one complete 

 revolution of the body in a uniform steep descending left spiral as a narrow channel in a deep 

 furrow, widening distally, and beyond the flagellar pore spreading out as a broad trough, one 

 side of which partly encircles the distal eminence of the hypoeone, forming a broad notch in 

 the outline of the body viewed dorsoventrally. 



The ocellus is of the concentrated type. It is situated 0.25 of the total length of the body 

 from the posterior end on the right of the distal end of the sulcus instead of the left, as usual 

 in Pouchctia, occupying a somewhat protruding, posterodextral portion of the epicone. Its 

 length is almost 0.25 transdiameter and its axis is horizontal with the lens directed to the left. 

 In a second individual it was directed anterodextrally 45° from the horizontal. It is composed 

 of a hemispheroidal melanosome with a brilliant red central core, partly surrounding the base 

 of the simple spheroidal lens of about the same size as the melanosome. The lens is a clear, 

 hyaline, asymmetrical sphere with faint indications of concentric layers and the melanosome is 

 without indications of amoeboid processes. In a second individual of larger size the melano- 

 some was flattened and twice the diameter of the somewhat elongated lens. Both lens and 

 melanosome were less symmetrical than in the individual figured. As cytolysis approached the 

 lens flattened into a disc with an axial button. 



The ellipsoidal or spheroidal nucleus is situated near or somewhat posterior to the middle of 

 the body. It is ellipsoidal in shape in the individual figured with major and minor axes of 0.6 

 and 0.4 transdiameter respectively. Chromatin strands follow its major axis. 



No pusules were noted in the encysted individuals examined. The cytoplasm is clear or 

 finely granular with few or many larger granules and oil globules. The individual figured 

 showed no granulations or vacuoles and but one large, rounded, ochraceous food mass enclosed 

 in a vacuole. 



The surface of the body presents no striations or other markings and there are no peripheral 

 vacuoles. In one individual, as cytolysis approached, minute lines and lenticels of colored fluid 

 gathered in the periplieral plasma with some indications of a longitudinal linear order 10-12 

 across one face. The color is amaranth purple diffused through the cytoplasm. The color may 

 become aggregated into small blotches or into strands or threads peripherally located as above 

 noted, leaving the adjacent cytoplasm colorless. Both individuals examined were contained in 

 thin, hyaline, close fitting cysts. 



DiiNiENSiONS. — Length, 59-68/*; transdiameter, 35-39^; axes of nucleus, 

 22-27/* and 1 6-22/* ; length of ocellus, 9/* ; its greatest width, 7.5/*. 



Activities. — Both individuals examined showed no active movements be- 

 yond continuous vibrations of the transverse flagellum without rotation within 

 the cyst. 



