KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 313 



Description. — The body is broadly ellipsoidal with broad apices, circular in cross-section, its 

 length 1.37 transdiameters at the widest part. The epicone and hypocone are subequal, the 

 epicone having a length greater by 0.12 of its length, but its transdiameter is less than that of . 

 the hypocone. The epicone has a length from the proximal and distal ends of the girdle of about 

 0.4 and 0.69 respectively of the total lengtli of the body. It is irregularly convex-conical with 

 broad, rounded apex. The hypocone has a slightly greater transdiameter than the epicone, 

 broad posteriorly', subtruncate with a broad, shallow sulcal notch. 



The girdle is a descending left spiral of 1.6 turns with a displacement of O.-l transdiameter. 

 Its distance from the apex at its proximal and distal ends is about 0.4 and 0.69 respectively of 

 the total length of the body. Its course for the proximal and distal third.s of its length is nearly 

 transverse, the greatest posterior deflection occurring in the middle third on the dextrodorsal 

 surface of the body. The furrow is relatively narrow, its width about 0.04 transdiameter, deeply 

 impressed, the excavation undercutting both borders slightly. 



The sulcus invades the epicone in a long apical loop which encircles the apex and terminates 

 ou the sinistrodorsal surface some distance posterior to the apex. The sulcus continues its spiral 

 course beyond the anterior junction with the girdle, with a sinistro deflection of 0.6 transdiameter 

 in the intercingular area before meeting the distal end of the girdle. Posteriorly it passes 

 directly to the antapex. where it forms a broad, shallow notch. The furrow is shallow and 

 slightly more than half as wide as the girdle. Posterior to the distal junction it becomes deeply 

 impressed, with the right border drawn out into a flap which nearly covers the channel. The 

 anterior flagellar pore opens at tlie proximal junction of the girdle and sulcus, the posterior pore 

 midway between the distal one and the antapex. It lies at the apex of the angle formed by the 

 right border of the sulcus and the furrow. The transverse flagellum traverses the entire length 

 of the girdle. 



The nucleus is an ellipsoidal body lying in the posterior part of the body near the distal 

 junction of the girdle and sulcus. Its major and minor axes are 0.44 and 0.33 transdiameter 

 respectively in length. 



The cytoplasm is very clear and transparent, its granular structure scarcely perceptible. 

 The anterocentral part of the body is filled with a large food mass showing traces of a dinofla- 

 gellate girdle, olive yellow in color with smaller, slightly darker granules of the same color. The 

 peripheral layer of c.ytoplasm is marked by a reticulum of vetiver green witli a background of 

 pale glaucous green. Nutrition is holozoic. 



Dimensions. — Lengtli, 62i^; transdiameter, 4;>; axes of nucleus, 20m and 15f*. 



Occurrence. — This was observed on July 20, 1917, 6 miles ofl La Jolla, 

 California, in a haul from 80 meters to the surface and in a surface temperature 

 of 21° C. 



Comparisons. — This is one of the most aberrant species in the genus Gyro- 

 diniiDii. Its sulcus strikingly resembles that found in Pouchrtin (as in P. 

 maciduta (pi. 11, tig. 119) and /'. schuctti (fig. PP, 10) in its well developed 

 apical loop, and is quite unlike that found elsewhere in the genus Gyrodiniiim. 

 Its length of girdle, amount of girdle displacement, and lack of an ocellus leaves 

 no doul)t as to its status generically. In its reticulate peripheral zone it 

 resmbles Coclilodininm cJarissiuiU)ii (pi. 5, fig. GO). 



It belongs in the sul)genus Lacviyclht, though it is not closely related to any 

 other member of that group. 



