134 MEMOIRS OF THE UNIVERSITY OP CALIFORNIA 



of epicone are found in A. truncatum, A. scissum, and A. sulcatum (figs. U, 

 3, 1, 10). The si^ecies is thus a divergent member of tlie section of the genus 

 having the larger epicone. 



Amphidinium corpulentum sp. nov. 



Plate 1, figure 11 ; text figures U, 6, 13 



Diagnosis.- — A small species with body stout, elongated rotund, its length 

 1.55 transdiameters, dorsoventrally compressed to about 0.5 transdiameter ; 

 epicone about 0.25 of the total length, girdle anterior, sulcus extending around 

 apex of epicone to antapex with left flap on hypocone, color ochraceous, littoral 

 habitat. Length, 46-54/^. Pacific at La Jolla, California, July, 



Description. — The body is stout, sack-shaped, its length 1.5-1.6 transdiameters, flattened 

 dorsoventrally to about 0..5 transdiameter. Epicone 0.20-0.25 of the total length, subconical in 

 outline with slightly convex sides forming an angle of 30° in ventral and 60° in lateral view. 

 Its diameter almost equals that of the epicone. Its height is 0.66 of its base in lateral view and 

 0.60 of the base in its greatest ventral extension. Its apex is broadly rounded and partially 

 encircled by the terminal loop of the anterior end of the sulcus. The hypocone forms 0.75-0.80 

 of the total length and has straight sides for 0.75 of its length. The antapex is broadly rounded 

 in a flattened semicircular outline scarcely notched by the distal end of the sulcus. 



The girdle curves sharply anteriorly at its proximal end at an angle of 45°, reaching the 

 horizontal at the end of the first quarter of the turn, continues horizontally to its distal quarter, 

 where it turns posteriorly at an angle of 30° without much curvature to its junction with the 

 sulcus. Its displacement posterior to its proximal end is about a furrow's width. The V-shaped 

 junction is thus markedly asjTnmetrical. The furrow is deeply incised with prominent lips. 

 The anterior flagellar pore opens at the junction of girdle and sulcus. The sulcus extends the 

 full length of the body in an almost rectilinear course from the antapex anteriorly upon the 

 epicone to within less than two furrows' width of the apex, where it makes an abrupt turn to 

 the left and forms a faint semicircle about the left side of the apex. It sinks deeply into the 

 hypocone and its left margin forms an overhanging flap. It flares distally at the antapex in a 

 broad posteroventral excavation. The longitudinal flagellum arises from the posterior flagellar 

 pore at a point about 0.33 of the length of the hypocone posterior to the distal end of the girdle. 

 It projects beyond the body for a distance equal to 0.75 of the total length of the body. 



The surface has no evident striations. The nucleus, in the individual shown in the figure, 

 was elongate, narrowly reniform, and was located in the right half of the epicone with its longer 

 axis parallel to the major axis of the body. Its length nearly equals the transdiameter and its 

 diameter was about 0.3 its length. The body was packed, especially in the peripheral regions, 

 with numerous small rounded ochraceous chromatophores which gave to the whole body a difli'use 

 pale yellow ochre tone. Pusules, amyloid body and oil globules were not noted. 



Dimensions. — Total length, 46-54/^; greatest transdiameter, 30-34/^; dorso- 

 ventral diameter, 17/^; length of nucleus, 26-30/*. 



OccuERENCE. — This species was found throughout July, 1914, in beach sand 

 off La Jolla, California. It was especially abundant during the latter half of 

 the month. 



