KOPOID AND SWEZY: UNARMORED DINOPLAGELLATA 201 



Description.— The body is large, subovoidal, widest near the equator with rounded apices, 

 circular in cross-section, its greatest length 1.66 transdiameters at the widest part. The epicone 

 exceeds the hypocoue in size, its length being greater by 0.2 of its own length. It is dome- 

 shaped with symmetrically rounded sides and broad, slightly crenulated apex. It has a length 

 on the left and right sides of 0.5 and 0.62 respectively of the total length of the body. The 

 hypocone is narrower tliaii tlie epicone with its sides less rounded, tapering posteriorly to the 

 broad, truncate antapex. This is deeply excavated by the suleal notch and its borders crenulated 

 by the surface ridges terminating in the furrow. 



The girdle forms a descending left spiral with a posterior displacement of its distal end of 

 0.22 transdiameter and an overhang of about 0.07 transdiameter. Its proximal end joins the 

 sulcus at a distance from tlie apex of 0.50 and its distal end 0.62 of the total length of the body. 

 The furrow is wide, about 0.07 transdiameter and deeply impressed, the borders, especially on 

 the anterior side, overhanging it, thereby reducing its apparent width by one-half. In some 

 forms the erenate surface is in evidence along the borders of the girdle, in others the crenulations 

 along the borders are obscure. The sulcus begins as a slightly enlarged pit at, or somewhat to 

 the left of the apex, passes posteriorly to the girdle in an almost straight line and continues its 

 course to the antapex in a sigmoid curve. The furrow is narrow anteriorly, enlarging to twice 

 its width at the girdle and again behind the region of the posterior pore. Near the antapex it 

 deepens to about 0.7 of the transdiameter of the body at that plane, forming a deep excavation 

 at the antapex. The anterior flagellar pore opens at the proximal junction of the sulcus and 

 girdle, the posterior pore a short distance below the distal junction. 



The cell contents consist of a spheroidal nucleus, a cluster of subspheriodal bodies varying 

 in color from light saffron yellow to dark orange yellow, small green rodlets and minute refractive 

 granules. The nucleus is located in the anterior part of the liypocone, just behind the girdle 

 and is filled with coarse, raoniliform chromatin strands and a single minute, excentrically located 

 nucleolus. Its axis is about 0.4 transdiameter in length. Large, spheroidal food masses were 

 present in all individuals examined, with only slight variations in size, color, and position. 

 Clustered around and among them were numerous dark purplish, highly refractive bodies. These 

 are double-contoured and presumably fatty in nature. A greyish pink pervades the cytoplasm 

 as a whole, fading out as the animal becomes moribund. A small club-sliaped pusule is connected 

 with the anterior flagellar pore by a long, slender canal. 



The surface is regularly marked by stout, longitudinal, equidistant, yellowish striae. These 

 are about the same in number on both epicone and hypocoue, about 23 across the ventral face 

 at the girdle, decreasing by extinction at various levels towards the apices, so that there is no 

 considerable approximation of the striae in these regions. They lie in the troughs of shallow 

 furrows, with rounded ridges between, which give a erenate appearance to the borders at the 

 girdle and at the apices. The small, slender, green rodlets are arranged at irregular intervals 

 along the ridges, at right angles to and immediately beneath the surface. 



Dimensions. — Length, 150-151^; transdiameter, 9(V; diameter of nucleus, 

 20/^. 



Occurrence. — Tliis species was first seen July Ki, IDOt), in a surface haul 

 witli No. 20 net, 1 mile off La Jolla, California. One individual was taken 

 June 25, 1917, with a No. 12 net in a haitl 6 miles off La Jolla, from 80 meters 

 to the surface and in a surface temperature of 18-3 C. It was found again 

 on June 28 under ai)proxiuiately the same conditions. It was noted July 2:5 

 and thereafter was (juite abundant, being roinid in most of the hauls taken up 

 to August 13. 



