KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 511 



The anterior flagellar pore lies in its proximal end a short distance in front of the lens and 

 the transverse flagelluni runs less than 0.75 of the length of the girdle. No paraeingular grooves 

 or bands were noted, and no attachment area detected. 



The sulcus begins oh the epieone above the girdle where it partially encircles the terminal 

 knob, and after its junction with the girdle it passes in almost a straight line posteriorly. It is 

 not displaced to the right by the deeply buried ocellus which somewhat underlies its iuter- 

 cingnlar region. It is a narrow slit closed by the overlapping right flap which forms a sharp 

 salient angle at the iipper end opposite the proximal end of the girdle. Posteriorly it opens out 

 into the large posteroventral tentacular recess. This cavity has an extreme length at the ventral 

 surface of 0.3 total length of the body and about half this on its dorsal side. From the middle 

 of its sloping anterior surface springs the prod. 



The prod, owing to the fact that the tentacular recess is not axially located but lies in the 

 ventral half of the body and has a sloping anterior wall, projects ventroposteriorly at an angle 

 of about 15° from the axis. It has a total length of about 0.75 transdiameter and projects for 

 about half its length beyond the margin of the recess. Within this cavity it has a thickened 

 shaft about 0.15 transdiameter in thickness, a constricted base, a somewhat sinuous course, and 

 is reduced to about one-third of this diameter in its extruded part which likewise has a sinuous 

 course. Its tip is blunt, without stylet and no circular or axial fibers were noted. No longi- 

 tudinal flagelluni was observed. 



The ocellus is of the compound type. It consists of a segmented lens and lobed pigment 

 mass. Its total length is 0.65 transdiameter, and its major axis is somewhat oblique to that of 

 the body. The lens consists of five rounded disks, appressed in a linear series decreasing a trifle 

 in size posteriorly, set slightly oblique to the main axis and parallel to and beneath the sulcus. 

 Their color is a clear glaucous blue with a tinge of yellow. Their diameter is 0.15 to 0.18 trans- 

 diameter and their thickness one-third to one-half their diameter. They rest lightly along a 

 part of the flattened face of the irregularly hemispherical pigment mass, and not in continuation 

 of its axis as is usually the case in the relation of lens and pigment. The pigment mass is bluntly 

 lobed in several regions and a small detached mass lies anterior to the line of lenses. The pig- 

 ment mass proper consists of an outer melanosome of black pigment and an inner core of reddish- 

 brown substance almost entirely concealed by the darker material. 



Pigment is found elsewhere in the body of this remarkable animal distributed in a very 

 characteristic and peculiar fashion. The periphery of the epieone and shoulders of the hypocone 

 are covered with a mantle of brilliant Brazil-red pigment distributed in the peripheral plasma 

 as a mottled reticulum formed of finely divided granules. These red reticulations extend 

 posteriorly down the ventral face on either side of the sulcus and become continuous with a 

 radial network of similar pigment sj)reading in all directions from a denser center near the 

 base of the tentacle. Several droplets of dark, clear rose-red pigment lie on the left side of the 

 sulcus posterior to the ocellus, and a single large droplet of the sanu' sort is found near the 

 proximal end of the girdle. Several linear masses of reddish-black pigment lie in tiie axis of 

 the distal part of the tentacle. This jiigment appears, in the main, to be distributed in regions 

 of itresumably greatest tension and most active oxidative processes, namely, the base of the prod, 

 and along the girdle and sulcus. There is no indication that this pigment is derived from the 

 food of the organism. 



The ellipsoidal nucleus has major and minor axes with lengths of 0.55 and 0.35 transdiameter 

 respectively and lies with the major axis at an angle of 45° to that of the body, far anterior. 

 No chromatin net was detected in its hyaline interior. There were no chromatophores or food 

 l)alls, rhabdosoines or peripheral vacuoles. No jjusules were noted. The cytoplasm was highly 

 translucent of a clear pearl-grey color, shading into a glaucous blue in the margins and along 

 the lateral grooves. 



