KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 491 



type found in one group of species in En/fliropsis, but not in PoncJietia. For 

 tliis reason Ave include tliis species in Erijthroims. It is a liiglily specialized 

 form, as well as the largest. 



Erythropsis cornuta (Schiitt) 



Plate 12, figure 129 ; text figures RR, 1 ; SS, 1 ; UU 



Pouchetia cornuta Schiitt (1895), pi. 26, figs. 96i.,. 



P. cornuta, Lemmermann (1899), p. 360. 



P. cornuta, Lang (1901), p. 161, fig. 75 A. 



P. cornuta, Pavillard (1905), p. 48, as synonym of Erythropxis agilis Hertwig. 



Diagnosis.- — A large species with ovoidal l)ody; length 1.25 transdiameters, 

 with distinct curved apical horn; girdle displaced 0.65 transdiameter; ocellus 

 protuberant ; lens simple, hemispherical ; pigment mass subhemispherical, with 

 red core; prod capitate, with terminal stylet, axially located. Length, 104/^. 

 Atlantic, Pacific, off La Jolla, California, July, August. 



Description. — The body is ovoidal, widest anteriorly, its length 1.25 transdiameters, dorso- 

 ventral and transdiameters equal. The epicone is small, its diameter in ventral view less than 

 0.5 transdiameter, apex broadly rounded with a short but very clearly differentiated hook- 

 shaped apical horn about two widths of the girdle in height and curved to the left. Ventrally 

 the height of the epicoue is only 0.25 transdiameter. except in the slender, posterior projection 

 along the distal end of the girdle which reaches a little beyond the middle of the body. The 

 epicone contains less than 0.15 of the total volume of the body. The hypocone has a length 

 midventrally of 0.75 of the total length of the body and much more dor.sally. Its anterior 

 region is contracted to about 0.5 transdiameter to meet the small epicone. Its right side is more 

 convex, its left somewhat flattened below the ocellus, aud the body contracts gradually posteriorly 

 to 0.4 transdiameter at its somewhat truncate antapex. 



The girdle originates at the anterior flagellar pore above the ocellus, forms a flat spiral 

 slightly below the anterior margin on the left and dorsal sides, and in the distal quadrant turns 

 posteriorly at an angle of about 30° from the horizontal, increasing to 70° in its most distal 

 region to its junction with the sulcus. The total displacement in the interciugular region is 

 0.65 transdiameter. The transverse flagellum reaches about 0.5 of the circumference. The 

 furrow is sharply but not deeply imjiressed and is bordered by parallel paradiuial lines. The 

 anterior paraciugular band is wider than the posterior, the former slightly exceeding, the latter 

 slightly less than the width of the furrow. These lines are clearly defined in this species. At 

 the distal end of the furrow on its anterior margin is a deej) pit, the attachment area, the i>oint 

 at which presumably the anterior horn of the posterior sehizont remained jointed to the anterior 

 sister cell at binary fission. The sulcus is a very narrow groove running from the anterior 

 flagellar pore obliquely posteriorly on the right side of the ocellus, curving again below it to the 

 left and continuing beyond the middle of the body to its junction with the tentacular recess. 

 This cavity is broadly and asymmetrically campanulate, with a dorsal ledge, a deep pit around 

 the shaft of the prod and a wide right flap which projects over the midventral region. Tlie 

 depth of the recess is 0.3 of the total length of the body. No longitudinal flagellum was seen, 

 but the posterior pusule may mark the point of its origin. 



The prod is elongate cylindrical, reaching, when extended, a total length 2.3 that of the 

 body, and when fully contracted retreating whollj' within the postinargin of the tentacular 

 recess. It is distinctlj' capitate distally, with a knob twice the diameter of the shaft at the 



