138 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



of about 0.79 of the total length of the body. It is narrowed anteriorly to about 0.66 of its widest 

 transdiameter, which is at the equator of the body midway between the apices. It tapers poster- 

 iorly to the rounded antapex, which is narrower and more pointed than the apex. 



The girdle is anterior in position, its distance from the apex being 0.2 of the total length of 

 the body on the dorsal and lateral sides. Ventrally both sides of the girdle are deflected poster- 

 iorly until they meet the sulcus at about 0.36 of the total length of the body from the apex. The 

 furrow is a narrow, rather shallow depression with smoothly rounded borders. The sulcus is a 

 narrow trough extending from the girdle to the antapex. The anterior flagellar pore is located 

 at the junction of the girdle and sulcus, the posterior pore at a point about 0.6 of the distance 

 between the junction and the antapex. 



The nucleus is a relatively small, spherical body found in the posterior portion of the hypocone. 

 It is filled with fine, moniliform chromatin strands. Its axis is about 0.37 transdiameter. Small 

 club-shaped pusules open into each flagellar pore. The c^-toplasm is finely granular, densely 

 so in the central portion of the body, with numerous blue green oil droplets scattered through it. 

 In the anterior end of the body a large vacuole is found and behind it a large food mass enclosed 

 in a vacuole. The general color of the organism is a yellow green with a trace of orange in the 

 denser parts. The surface is finely striate with minute blue green rodlets arranged in a linear 

 series, interspersed at every third row with continuous lines, equidistant and longitudinal. In 

 additon the surface of the hypocone is deeply impressed with longitudinal, parallel grooves. 

 These are arranged in groups of four and are relatively short, fading out before reaching the 

 girdle and antapex. None could be detected on the epieone. 



Dimensions. — Length, 85^*; transdiameter, 53a*; diameter of nucleus, 20^. 



Location. — This was first seen July 20, 1906, in a surface haul made with 

 a No. 20 net, 1.5 miles off La Jolla, California. Two individuals were taken 

 July 27. 1917, 4 miles off La Jolla, in a haul from 80 meters to the surface and 

 in a surface temperature of 21 °9 C. 



Comparisons. — This species and A. cucnr'bita are the only ones in the genus 

 which present the peculiar combination of deeply marked furrows and fine 

 striae on the surface. These differ slightly in the two species. The cytoplasmic 

 structure is simpler in this species than in .1. cucurhita, yet presents the same 

 e\ddences of holozoic nutrition. 



Amphidinium dentatum sp. nov. 



Plate 10, figure 111 ; text figure U, 4 



Diagnosis. — A small species with hody broad, almost squarish in ventral 

 view, dorsoventrally compressed, its length 1.25 transdiameter; girdle anterior, 

 without displacement; sulcus extending from girdle to hy^Docone; blue green 

 chromatophores ; littoral habitat. Length, 40^. Pacific at La Jolla, California, 

 August. 



Description. — The body has an almost squarish outline in ventral view, dorsoventrally com- 

 pressed to about 0..5 transdiameter, widest in the middle, its length 1.25 transdiameters at the 

 widest part. The epieone is small, triangular in ventral view with a width of 0.75 transdiameter. 

 It extends posteriorly on the ventral side about 0.3 of the total length of the body, its sides 

 forming an angle of 70°. It is slightly asymmetrical with tlie left side higher than the right. 

 The apex is a short, toothlike, dextrally flexed projection. The hypocone is broad and rotund 



