KOPOID AND SWEZY: UNAKMORED DINOFLAGELLATA 137 



A small club-shaped pnsule opeus into each flagellar pore. The cytoplasm is coarsely granular, 

 with a great complexity of structure in all the individuals observed. The midventral portion 

 of the body in the region of the pusules is usually filled with numerous small, dark, refractive 

 granules. Most of these have been omitted in the figures for the sake of clearness. Dorsad from 

 these are large vacuoles, and radiating out from them towards the surface of the body are 

 numerous long, slender greenish rodlets interspersed between long, narrow vacuoles. Both the 

 anterior and posterior regions are filled with large vacuoles or food masses. Small oil droplets 

 are scattered through the remaining cj-toplasm. 



Vacuoles containing fluid of the same pink color as the pusules are usually present. The 

 general color is a deep, rich yellow. 



The surface of the body on the hypocone is marked with deep, parallel furrows, about 20 in 

 number in the circuit of the body. These may be arranged in groups of 3, 1, 5, or may be 

 equidistant. They usually die out before reaching the girdle and the antapex. Between the 

 furrows are found fine equidistant, parallel surface lines of dots, usually about eight between 

 furrows. 



Di:\rENSiONS. — Length, 95 to 110/^; transdiameter, 75^; axes of nucleus, 32 

 and 23i^. 



OccuRREXCE. — The first individual was taken July 12, 1917, 4 miles off La 

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

 temperature of 20?5 C. Three individuals were recorded July 20, in a haul 6 

 miles offshore from 80 meters to the surface and in a surface temperature of 

 21° C. Four more were taken July 27, 4 miles offshore at the same depth and 

 at a surface temperature of 21-9 C. The same number was again observed 

 AugTist 21, in a catch taken 5 miles oifshore, in a haul from 83 meters to the 

 surface and in a surface temperature of 21?6 C. 



Comparisons. — This is by far the largest species of Amphidinium thus far 

 descril)ed. It presents undoubted affinities with that group, however, as sIionati 

 by the relatively small, operculum-like cpicone. Its large size, rotund habit, 

 and presence in tlie deeper oceanic waters make it a possible connecting link 

 with Gymnodinium. It also exhibits cytoplasmic diffei-entiation similar to that 

 found in G. dogieli and G. costatnin, and without parallel elsewhere in the genus 

 AmpJiidinium. 



Amphidinium cucurbitella sp. nov. 



Plate 1, figure 6 ; text figure U, 30 



Diagnosis. — This is a medium sized species with broad almost biconieal 

 body, its length 1.6 transdiameters; girdle anterior, without displacement; 

 sulcus extending from girdle to antapex; surface striate and furrowed; color 

 green, holozoic. Length, 85^. Pacific off La Jolla, California, July. 



Description.- — The body is broadly ellipsoidal, approaching biconieal (50°), widest in the 

 middle and tapering towards both apices, its lengtli 1.6 transdiameters at the widest part, sub- 

 circular in cross-section. The hypocone greatly exceeds the small cpicone, its length being greater 

 by 0.53 of its own length. The epicone is small, rounded, cai)like, with a longer, pointed ventral 

 l)ortion. It has a length above the anterior flagellar pore on the ventral side of 0.36 and on the 

 dorsal side of 0.2 of the total length of the body. The hypocone has a length on the dorsal side 



