1911] Kofoid: Gonyaulax catenata. 291 



Gonyaulax catenata (Levander) Kofoid 



PI. 18, figs. 1-7. 



Glenodinium cinetum, Pouchet (1883), p. 441, pi. 20/21, fig. 36, /ide 



Cleve (1901a), p. 256. 

 Peridinium eatenatum Levander (1894), pp. 1-19, pi. — , figs. 1-10. 

 P. eatenatum, Van Hoffen (1897), p. 267, pi. 5, fig. 5. 

 Amylax catenata, Meunier (1910), p. 52, pi. Ibis, figs. 46, 47; pi. 3, 



figs. 28-34. 



Diagnosis : A minute species with the general form of a 

 Peridinium but the plates of Gonya\dax. Plate formula i', 4", 

 6", 6, 6'", 1'', 1"" . Posterior plate of ventral area exceeding 0.5 

 transdiameter in width. Several antapical spines present. Ring 

 shaped starch grains. Fission with chain formation. 



Description: Body rounded, flattened dorso-ventrally, length 

 0.85-0.95 transdiameter, dorso-ventral diameter (between levels of 

 extremes) 0.75 transdiameter, in middorsal line about 0.5 transdiameter. 

 ('ross-section at girdle reinform. Epitheca slightly exceeds hypotheca, 

 its right shoulder convex, its left slightly concave, its altitude 0.47 

 transdiameter, contracted distally to a low apical horn scarcely differ- 

 entiated, with apex attaining a girdle with across and guarded laterally 

 by two spine-like extensions of the apical plates (pi. 18, fig. 4). Hypo- 

 theca low and wide with concave postmargin 0.6 transdiameter across, 

 its altitude 0.4 transdiameter, deeply excavated ventrally. 



Girdle equatorial, descending, displaced distally 1 girdle width, with- 

 out overhang, often constricted middorsally (pi. 18, fig. 4) near the 

 fission line (between girdle plates 3 and 4). The furrow is deeply 

 impressed, with scarcely salient ridges, and no fins. The ventral area 

 is exceptionally open, very slightly indenting the epitheca and expanding 

 posteriorly to a width of 0.6 transdiameter and reaching the postmargin. 

 Its width at the distal posterior girdle ridge equals or exceeds that of 

 the girdle. 



The plate formula is i', 4", 6", 6. 6'", li\ 1"" (pi. 18, figs. 1, 2). Apical 

 1' is very slender, about 0.3 girdle width across, 2' and 4' are elongated 

 in the longitudinal and 3' in the transverse direction. The anterior inter- 

 calaries In-d" are very uneven in size, 1" and 4" on the left and right 

 shoulders, and S" superposed (anteriorly) upon 3" near the middorsal 

 line. Frecingidar 6" is quadrangular and postcingular 1'" nearly square, 

 1 girdle width across and 1.5 long. Posterior interccdary IP is much 

 wider than long. The anterior plate of the ventral area (pi. 18, fig. 5), 

 is deeply notched on its posterior margin by the flagellar pore and a 

 small extension meets apical 1'. Two intermediate plates (int. pi., pi. 

 18, fig. 1) of nearly equal size are plainly discernible and the wide 

 posterior plate (post, pi.) reaches the postmargin and extends from the 

 left antapical spine to the right face somewhat above the right spine. 



