KOPOID AND SWEZY: UNARMORED DINOPLAGELLATA 501 



peripheral vacuoles which are close set as in E. cochlea (Schiitt), but through- 

 out the surface the individual vacuoles exhibit an anteroposterior elongation 

 wholly lacking in E. cochlea. The salmon-pink color is also unique. 



Erythropsis labrum sp. nov. 



Plate 12, figure 132 ; text figure SS, 6 



Diagnosis. — Ijarge sized species with ellipsoidal body, its length 1.33 trans- 

 diameters; girdle displaced 0.2 transdiameter ; sulcus with overlapping, anter- 

 iorly directed flap on right side; ocellus deeply imbedded; lens composed of 

 seven spheroids ; pigment mass deeply and irregularly lobed, black, with yellow- 

 ochre core and widely scattered granules ; prod capitate, without stylet ; periph- 

 eral vacuoles elongated longitudinally, scattered irregularly. Length, 111/^. 

 Pacific off La Jolla, California, August. 



Description. — The body is broadly and not quite symmetrically ellipsoidal, its length 1.33 

 transdiaraeters measured at the widest part which is at the middle. The dorsoventral diameter 

 is a trifle less than the transverse. The right side is evenly convex and the left and dorsal are 

 somewhat flattened. The left side of the body extends somewhat farther posteriorly, as in the 

 case of the left horn in Ceratium. The epicone is much flattened, forming a low cone whose 

 base has a diameter of 0.7 transdiameter and an altitude at the proximal end of the girdle of 

 0.18 of the total length of the body and of 0.33 at the distal end on the right ventral side. 

 Dorsally its lower margin scarcely lies below the summit so that its surface slopes mainly to 

 the right and ventrally and constitutes as a whole less than 0.1 of the total surface. It has no 

 distinct apical horn, although there is a slight hump at the right of the tip of the sulcus. The 

 hypocone forms over 0.9 of the body, is slightly contracted posteriorly, and has a broadly rounded 

 antapex, slightly cleft by a broad groove from the tentacular recess, with the lobe on the left 

 about two widths of the furrow longer than that on the right. 



The girdle ascends steeply from the anterior flagellar pore to almost the anterior margin 

 along the dorsal side, then turns posteriorly with a reversed curve on the ventral face, so that 

 the total intercingular displacement is about 0.22 transdiameter. It makes a complete turn 

 around the body, but its junction with the sulcus is hidden by the anterior lobe of the flap of 

 the right side of the sulcus. The furrow is rather deeply impressed and is about 0.03 trans- 

 diameter in width. It is paralleled by paracingular lines or precingular and postcingular grooves 

 equidistant from the furrow, each about a width of the furrow removed from its margins. 



The sulcus extends from apex to antapex, fading out anteriorly in a feebly marked loop at 

 the left of an apical hummock, the homologue of the liorn of E. cornuta-. It makes a flat, reversed 

 curve as it joins the girdle at the anterior flagellar pore, passes to the right of the -lenses, joins 

 the distal end of the girdle beneath the anterior flap, and then widens out into the deep, axially 

 located, tentacular recess. This recess and the intercingular section of the sulcus are hidden 

 beneath the widely overlapping; right flap (hence the specific name labrum) which extends anter- 

 iorly as a free lobe from the distal end of the girdle, so far as to cover over the anterior flagellar 

 pore. This flap is notched at the tip, which morphologically is near to the posterior border of 

 the distal end of the girdle. The anterior border in this region in some species, as in E. cormita 

 (pi. 12, fig. 129), soinetimi'S bears a notch which marks the attachment area where the anterior 

 end, possibly the anterior horn, of the posterior seliizont is attached to the body of its sister cell, 

 the anterior schizont. It may well be that this notch in the posterior border is due to the same 

 cause, the final attacliment of tlir two jiarliiig seliizonts (Kofoid and Swczy, 1917). 



