44 



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



Ceratocorys skogsbergii n.sp. 

 (Figure 58) 



Dimensions . One of the smallest species of the 

 genus. Length of body ( 1_) 66 (63-69) microns. Diame- 

 ter (d) 58 (56-59) microns. Two specimens were meas- 

 ured. 



Shape . Similar in general appearance to C. aultii 

 of Euceratocorys . Body longer than broad. The j/d 

 ratio is 1.15 (1.13-1.17). Epitheca of medium height, 

 with girdle placed well forward. The e/l_ ratio is 0.33 

 (0.32-0.34). Girdle displaced about 0.5 girdle width. 

 Body almost circular in apical view (fig. 58B). Hypothe- 

 ca squarish at antapex; somewhat constricted near mid- 

 dle. Antapex broad, so that sides of hypotheca do not 

 converge at a great angle with longitudinal body axis. 

 The angle 15.°5 (15°-16°), the smallest of any species 

 for which this angle could be measured. The postero- 

 ventral corner of antapex is truncated obliquely at an 

 angle of about 45° to longitudinal axis (fig. 58D). Dorsal 

 hypothecal plates (po4 and po5) extend to and around 

 antapex, forming part of the most posterior end of body. 

 Antapical plate alone forms the obliquity and is not 

 rounded so as to form antapex, as is the case in C. hor - 

 rida (fig. 47E). 



Body wall . Surface covered with small pits. Inter- 

 calary zones may have small irregular markings and 

 pores. Ventral area variously ornamented with reticu- 

 lations and pores (fig. 58A). Ventral epithecal pore in- 

 conspicuous. 



Plate pattern . Second anterior intercalary some- 

 times touches apex and thus becomes, actually, an apical. 

 It is usually wide enough to be quite evident. 



Lists. Girdle lists small, about 1 girdle width wide. 

 Strengthening ribs regularly spaced, usually running out 

 from body wall. When the girdle plates are dissected 

 away from the body plates to which the girdle lists are 

 attached, an extremely thin membrane is seen to be at- 

 tached to the girdle plate. In intact specimens this 

 membrane lies in contact with the list. Transverse gir- 

 dle lists fairly well developed. Body lists, except the 

 ventral one, not well developed. Body sutures may or 

 may not be indicated by such lists. The ridge to the 

 right of flagellar pore rises to meet pol, forming an 

 arch over the posterior part of pore. 



Spines . Dorsal and ventral spines absent. Antapi- 

 cal spines three; straight and simple, about 2.5 girdle 

 widths long, placed at dorsal, ventral, and left corners 

 of antapical plate. They were not connected by lists in 

 the specimens examined, although the left sulcal list ran 

 onto the ventral spine. 



Reproduction . Evidence of fission was not found. 



Distribution . This species was found at 10 of the 

 Carnegie stations, all in the Pacific. There are 11 rec- 

 ords of occurrence, all rare. The species exhibited a 

 tendency to be more common at the surface, with 5 rec- 

 ords for the surface, 4 for 50 meters, and 2 for 100 me- 

 ters. There are 2 pump records and 9 net records. 



In its geographic distribution, this species was re- 

 stricted to the southern and western Pacific (fig. 52). 

 There was 1 station off Japan (station 113), 2 in the 

 North Equatorial Current (stations 91 and 100), 4 east 

 of Samoa, and 3 southwest of Easter Island. 



The surface temperatures at the stations where the 

 species occurred at any depth varied from 22°. 8 to 

 28° 7 C. The ranges of hydrographic conditions in situ 

 were as follows: temperature, 21°5 to 28°.7 C; salinity. 



34.7 to 36.2 o/oo; pH, 8.22 to 8.39; phosphate, 8 to 40 

 mg P04/m3. 



This is a very rare tropical species. There are so 

 few records of its occurrence that no distributional cor- 

 relation would be significant. There were 2 records of 

 its occurrence in water with less than 10 mg P04/m3. 

 Type locality: Carnegie station 51a. 



Ceratocorys gourretii Paulsen 

 (Figure 59) 



Ceratocorys g ourretii Paulsen, 1931, p. 36. 

 Phalacroma" j ourdanii Schutt, 1895, p. 64, pi. 4, fig. 20, 



1-4. Entz, 1902, p. 130, figs. 6-8. Entz, 1905, pp 



111, 113, figs. 1-4. 



Ceratocorys horrida, Murray and Whitting, 1899, p. 329, 



pL 30, fig. 5a. 

 Phalacroma Ceratocorys Entz, 1902, pp. 135-144, figs. 



ys 



26, 33. Entz, 1905, pp. 120-127,'figs. 22-28, pp. 



Ill, 134-142. 

 Ceratocorys j ourdanii Kofoid, 1910, pp. 183-185. Forti, 



1922, p. 84, pi. 6, fig. 74. Dangeard, 1927c, p. 343, 



fig. 7b. Pavillard, 1931, p. 101. Matzenauer, 1933, 



p. 452, fig. 21. 

 not Dinophysis j ourdanii Gourret, 1883, p. 79, pi. 3, fig. 



55 (=C. horrida Stein). 

 ? Dinophysis g ales , Pouchet, 1883, p. 28, fig. G, no. 3. 

 ? Dinophysis j ourdanii , Klebs, 1884. 

 ? Dinophysis armata Daday, 1888, p. 193, pi. 3, fig. 6. 



Dimensions . Smallest species of the genus. Length 

 of body (i) 49 (38-62) microns. Diameter (d) 42 (28-55) 

 microns. Greatest diameter of body in ventral view 48 

 (34-60) microns. Nineteen specimens were measured. 



Shape . Body unique in its subspherical to obovoid 

 shape, with absence of the angularity characteristic of 

 other members of the genus. The pronounced curvature 

 of the body causes the anterior circumference of the gir- 

 dle to be considerably shorter than the posterior (fig. 

 59D, E, F, G). Body circular to subovate in apical view 

 (fig. 59B), always slightly longer than wide. The h/^ 

 ratio is 1.22 (1.06-1.57). Angle ;6 not measured fortius 

 species because of curvature of lateral margins. Epi- 

 theca low dome-shaped, with girdle far forward as in the 

 genus Phalacroma, with which the species has been con- 

 fused. The e/l_ ratio is the smallest in any species of 

 the genus: 0.20(0.16-0.22). Greatest width of body a- 

 bout halfway from girdle to antapical margin. Girdle 

 displaced about 1 girdle width. 



Body wall . Thecal wall regularly covered with very 

 small pits. Ventral epithecal pore conspicuous. In in- 

 tercalary zones the pits are either absent or fewer than 

 on original portions of plates (fig. 59H). 



Plate pattern . Second anterior intercalary narrow 

 and hidden between lists. Sometimes no other plates are 

 indicated by lists except at left side of sulcus. First 

 postcingular reduced to a small triangular plate joining 

 anterior sulcal and second postcingular plates. It forms 

 left edge of flagellar pore. Second postcingular more 

 distally located than anterior sulcal plate and partly 

 overhangs the pore as the first postcingular does in the 

 subgenus Euceratocorys . Right accessory sulcal plate 

 long. Right sulcal plate comparatively short, so that it 

 barely touches flagellar pore (fig. 59A). 



Lists . Girdle lists about 1.5 girdle widths wide, 

 strengthened by cross ribs running either from body or 

 from outer edge of lists. Partitioning lists on the gir- 

 dle not well developed. Right and left sulcal lists al- 

 ways quite evident, as are the lists bordering a2 and the 



