KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 391 



Torodinium robustum sp. nov. 

 Plate 4, figure 49 ; text figure II, 1-3 



Gymnodinium tcredu, »Schutt (iy95), iu part, pi. 23, figs. 74j_.. Figs, l-i^^n, are 1\ teredo 

 (Pouchet). 



Diagnosis. — Medium sized species, elongated, fusiform, its length 2.8 to 3.2 

 trausdiameters; epieone 0.83 to 0.85 total length; hypocone minute, conical, 

 as_A^nmetl'ical ; girdle a descending left spiral, displaced slightly; sulcus with 

 torsion of 0.4 turn proximally and 0.75 reversed turn iu apical region. Letigth, 

 67m to 75/^. Atlantic or Bay of Naples ; Pacific otf La Jolla, California, July. 



Description. — The body is elongate fusiform, with little taper, slightly fuller anteriorI,y, 

 widest at the middle, its length 2.8—3.2 trausdiameters measured at the widest part near the 

 middle. The epicoue greatly exceeds the hypocone, its length at the proximal end of the girdle 

 0.83-0.88 total length, while at the distal end it almost reaches the antapex, apex broadly 

 rounded; hypocone reduced to a luinute asymmetrical cone which with the girdle above it takes 

 on the form of the tip of an augur (fig. II, 1-3, hyp.). Its length at the proximal end of the 

 girdle is 0.12 to 0.15 of the total lengtii, and its diameter 0.3 to 0.4 transdiaraeter. It is quite 

 asymmetrical with its antapex towards the right (of the body) of the major axis when viewed 

 ventially, that is, with the anterior pore midventral. Its ventral slope is about twice as long as 

 the dorsal. It forms a lopsided cone of 70°-90°, according to the view or degree of contraction 

 and its antapex is pointed. 



The girdle is a descending left spiral slackening distally, displaced about twice the width 

 of its furrow, its distal end merging directly with the distal end of the .sulcus (fig. II, 1-3, gir.). 

 The furrow is deeply impressed with prominent, overhanging lips. The diameter of the body 

 in the oblique gii'dle is only about 0.35 transdiameter. The sulcus runs almost from apex to 

 antapex. Assuming for purposes of description that the location of the anterior flagellar pore 

 establishes the planes of orientation of the bod.y as a whole we may define the course of the 

 sulcus as follows. It begins very near the anterior end with a reversed loop of neai-ly 0.75 turn, 

 that is, running from the left side of the body around ventrally to its right instead of the usual 

 spiral course seen in the torsion of the sulcus. This loop is deflected posteriorly 10°-15° below 

 the horizontal, increasing posteriorly to within less than a transdiameter of the anterior end, 

 where it has turned to a posterior direction, which it then pursues longitudinally a little to the 

 right of the middorsal line. At 0.5 transdiameter from the antapex it turns iu the customary 

 descending left spiral for 0.4 turn at 25° below the horizontal to its junction with the girdle. 

 Its course below this point is a short expanded area on the ventral face of the button-like 

 hypocone. The transverse flagellum encircles the body and the stout posterior flagellum is one 

 transdiameter in length. Both arise close together near the proximal end of the girdle. 



The nucleus is an elongated rod with rounded ends, 0.5 of the length of the body in length 

 and slightly wider posteriorly. Its length is six times its middiameter. It is traversed by about 

 ten coarse, moniliform chromatin threads which form a steep spiral about its main axis. The 

 nuclear membrane is very faint and the nucleus remarkably difficult to discern in life. From 

 the anterior flagellar pore there runs anteriorly at the left of the nucleus a slender canal, the 

 ant(!rior pusule. No posterior pusule was found. On the left side of the body are four con- 

 tinuous linear peripheral "ehromatojihores" or rhabdosomes, which were a pale oural green in 

 our specimens. Schiitt (1895) figures them as of the same pale ochre as those of his other 

 figures of G. teredo. They are 0.65 of the total length of the body in length, equidistant and 

 somewhat unequal in length. Grouped about a central oil globule in the sinistroventral part 

 of the ai)ical region is a partial chromatophore ( ?) star of eight or nine rays grouped mainly 



