48 



STUDIES IN THE MORPHOLOGY, TAXONOMY, AND ECOLOGY OF THE PERIDINIALES 



regions." (Kofoid, 1911a, p. 196.) 



Remarks . The present diagnosis of the genus will 

 undoubtedly be radically revised upon a more intensive 

 study of the morphology of the species now included in 

 the genus. Judging from the results of the careful dis- 

 section of the two species included in this report, it can 

 be concluded that many of the specific diagnoses are 

 probably in error. In addition to this, it is likely that 

 the genus as now conceived Includes several groups of 

 generic status. 



In his first diagnosis of this genus, Kofoid {1907b) 

 gave the plate formula as 6ap, 6pr, 6po, lant, 1 longi- 

 tudinal ventral furrow plate, 1 girdle plate. Apparently 

 this analysis was made without dissection of the plates, 

 and the many ridges and markings of the theca led to an 

 erroneous conclusion as to the plate pattern. Later, 

 Kofoid (1911a) stated that his first interpretation was in 

 error and gave a new diagnosis which agrees much 

 more closely with that found in the two species present- 

 ed here. His new formula is "Sap, Oa, 6pr, 6g, 6po, Ip, 

 lant, ventral area consisting of a narrow anterior plate, 

 large posterior plate, and at least three intermediate 

 plates." In the present investigations complete dissec- 

 tions were made of the entire skeleton of G. pacifica and 

 G. fuslformis . The plate formula of these two species 

 is as follows: Sap, 2a, 6pr, 6g, 6-7s, 6po, Ip, lant. 



Whedon and Kofoid (19S6) made an analysis of two 

 new species, G. catenella and G. acatenella . The for- 

 mula for each of these is the same, viz., 4ap, Oa, 6pr, 

 6g, 5s, 6po, Ip, lant. This formula is sufficiently dif- 

 ferent from that of G. pacifica and G. fusiformis to jus- 

 tify generic separation. Gonyaulax pacifica and G. fusi - 

 formis have one less apical, two (instead of no) anterior 

 intercalaries, and two more sulcal plates. The facies 

 of the ventral part of the epitheca as well as the size 

 and shape of the body generally of Whedon and Kofoid' s 

 two species is quite different from those of G. pacifica 

 and G. fusiformis . 



The present work on the genus Gonyaulax shows 

 clearly that a complete reclassification of this and re- 

 lated genera is quite necessary. A re- examination of 

 the whole group on the basis of thorough morphological 

 studies is absolutely essential. Quite new conceptions 

 of relationships within the group will undoubtedly result 

 from such a critical analysis of extensive material. As 

 an example of a realigning, resulting from such thor- 

 ough studies, it may be mentioned that G. ceratocoroides 

 Kofoid has been placed in a separate genus. 



Gonyaulax pacifica Kofoid 

 (Figure 62) 



Gonyaulax pacifica Kofoid, 1907b, p. 308, pi. SO, figs. 37- 

 39. Kofoid, 1911b, p. 235, pi. 15, fig. 35. Pavillard, 

 1931, p. 51. 



Steinlella cornuta Karsten, 1907, pp. 348, 420, pi. 53, 

 HgT?. 



Dimensions . Length of body, exclusive of antaplcal 

 spine (I), 155 (131-263) microns. Transdiameter (d'), 

 80 (52-105) microns. This diameter Is the greatest di- 

 ameter, not the diameter seen in true ventral view (see 

 below). Width of girdle, about 5 microns. Twenty-two 

 specimens were measured. 



Shape . Body about twice as long as greatest diam- 

 eter. Thei/d' ratio is 1.98 (1.66-2.65). Body extreme- 

 ly asymmetrical, probably as a result of a differential 



growth in which the left side has grown decidedly larger 

 than the right. The short diameter (d) is about 0.6 

 times the long diameter (d') (see fig. 62D). Epitheca 

 compressed dorsoventrally, very abruptly from the gir- 

 dle so that the distal half of the epitheca extends as a 

 bladelike horn (fig. 62A, C, I, J). Hypotheca also very 

 strongly compressed dorsoventrally, but here the com- 

 pression is accompanied by a strong dorsal curvature 

 of the body which results in a concavity on the ventral 

 face and in an extreme approximation of the dorsal and 

 ventral'waUs of the hypotheca, especially on the right 

 side. Thus, the more posterior part of the hypotheca is 

 concave blade-shaped and the entire hypotheca is "scoop- 

 like" as Kofoid (1911a) described it. Posterior edge of 

 body rounded in ventral view with extension on left side 

 terminated by a spine which is from 1 to 2 girdle 

 widths long. The asymmetrical shape of the body re- 

 sults in quite different contours when the body is viewed 

 from slightly different angles. Figure 62A shows a 

 specimen presenting its widest ventrolateral aspect, and 

 figure 62H, a strictly ventral view, presents a narrower 

 body diameter but shows the broadest view of the ven- 

 tral area. 



Girdle slightly behind the middle; sinistral; ends 

 curved ventrally, particularly the proximal end; dis- 

 placed 1.5 to 3.0 girdle widths, no overhang; greatly ex- 

 cavated, often as much as 1 girdle width (fig. 62B). 



In connection with the unequal development of the two 

 sides of the body, there has been a rotation of the long 

 axis of the sulcus and ventral area so that in ventrolat- 

 eral view only the right side of the ventral area is visi- 

 ble. Ventral area more or less elliptical in outline, 

 somewhat sigmoid in ventral view but not in the flat ven- 

 trolateral view. Anteriorly the area extends into the 

 epitheca about 3 girdle widths. Greatest width of area 

 attained about halfway to antapex. Posteriorly the area 

 tapers to a point about 2 girdle widths from base of ant- 

 apical spine. Sulcus a deep groove on left side of ven- 

 tral area. Flagellar pore narrow and long (about 3 gir- 

 dle widths), sigmoid in outline, following the curvature 

 of the ventral area (fig. 62K), and extending posteriorly 

 from proximal end of girdle. 



Plate pattern . The three apical plates very imequal 

 in size. First apical very narrow with narrow extension 

 to girdle (fig. 62C). Apical closing platelet present, 

 sometimes loosely attached to anterior end of first api- 

 cal plate. Kofoid (1911a) stated that the platelet is a 

 definite part of the first apical, but the writer has found 

 that it may be detached quite easily. Second apical plate 

 is large and composes almost all of distal end of apical 

 horn. It has a Umb projecting arotmd the apex to right 

 side and fitting into a shoulder of first anterior interca- 

 lary (fig. 62D, I). Third apical a long triangiilar plate 

 with its apex at apex of specimen and its base along mar- 

 gin of second anterior intercalary (fig. 62C, D). This 

 apical was shown in Kofoid's (1907b) earlier drawing, 

 but he later (1911a) rescinded his earlier diagnosis of 

 this species and omitted this plate. 



First anterior intercalary, a large plate running 

 almost to apex, where it has a shoulder into which fits 

 the projection of a2. This plate was included in apS by 

 Kofoid (1911a), who apparently had not separated it from 

 that plate. The second anterior intercalary hasnotbeen 

 reported before for this species, but was easily deter- 

 mined in all specimens examined. It is probably homol- 

 ogous with al in Splraulax kofoidii . It frequently bears 

 a double ridge running transversely across its middle 



