24 



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



temperature, 20°5 C; salinity, 36.4 o/oo; pH, 8.23; 

 phosphate, 58 mg P04/ni3. Type locality: Carnegie 

 station 2. 



Peridlnium claudicanoides n.sp. 

 (Figure 29) 



Dimensions . Length of body (i) 166 (154-180) mi- 

 crons. Diameter (d) 141 (123-150) microns. Width of 

 girdle about 5 microns. Ten specimens measured. 



Shape . Mid-body similar to that of P. depressum . 

 The angle a. is 94° (79° to 101°). The h/d ratio is 0.75 

 (0.53-0.94). The body is compressed along an antero- 

 ventral-posterodorsal axis, running at an angle of about 

 55° to the plane of the girdle. The epitheca tapers into 

 a short truncated apical horn which is flattened lateral- 

 ly at the end so that it is from 1.1 to 1.5 times as wide 

 in lateral as in ventral view. The horn extends along an 

 axis which lies at an angle of about 65° to the axis of 

 depression of the body. The hypotheca terminates in two 

 stout pointed antapical horns which are more or less 

 triangular in outline. The a/d ratio is 0.30 (0.27-0.31). 

 The b/a ratio is 0.28 (0.23-0.35). In lateral view the 

 axis of the right antapical horn is in line with the axis of 

 the apical horn, but in ventral view it is seen to diverge 

 to the right. The left antapical horn is shorter than the 

 right and diverges from it laterally and ventrally. The 

 girdle follows approximately the same course as in jP. 

 depressum . 



Plate pattern . The tabulation of the epitheca is of 

 the second symmetrical, rarely the first asymmetrical, 

 pattern. Tabulation of other parts of theca as in P. de- 

 pressum. 



Body wall . The external surface of the theca is 

 faintly marked with an irregular reticulation which is 

 raised at the intersections so that under low magnifica- 

 tion the surface appears spinulose. Pores are scattered 

 irregularly over the surface, and bear no relation to the 

 reticulations. 



The plates are bordered by simple sutures or wide 

 intercalary zones. Rabbet joints occur as in P. depres - 

 sum. 



Comparisons . This species is close to P. depres - 

 sum . The mid-body has about the same form as in that 

 species although somewhat more expanded in the girdle 

 region, as is expressed by the low angle. It differs fur- 

 ther from P. depressum in the shorter and stouter api- 

 cal horn, and in the stout cuneate antapicals. Further- 

 more, it may usually be distinguished from P. depres - 

 sum by its plate pattern, which is the second symmetri- 

 cal. The last feature is not quite reliable, however, 

 since one specimen was found with the first asymmetri- 

 cal pattern, a tabulation occurring frequently in P. de - 

 pressum. 



Distribution . P. claudicanoides was found at 9 sta- 

 tions: 5 in the Atlantic and 4 in the Pacific (fig. 20). 

 There are 13 records of occurrence: 11 rare, 1 occa- 

 sional, and 1 common. It was found more often at the 

 surface, with 7 records for the surface, 3 for 50 meters, 

 and 3 for 100 meters. There are 11 net records and 2 

 pump records. The species was found in May in the north 

 temperate regions of the Atlantic, and in October and 

 November on both sides of the equator in the tropical 

 Pacific. 



In the Atlantic this form was found at four stations 

 in the North Atlantic West Wind Drift, stations 1, la, 2, 



and 3; and at one station in the Caribbean, station 32. 

 In the Pacific it occurred only off the coast of Colombia 

 and Ecuador, stations 35, 35a, 35b, and 40. It is thus 

 much more restricted in its distribution and occurs In 

 the Pacific at quite different places from P. depressum . 



The surface temperatures at the stations where it 

 occurred at any depth varied from 15°.5 to 28°.0 C. The 

 ranges of hydrographic conditions in situ were as fol- 

 lows: temperature, 13°8 to 27!0 C; salinity, 30.0 to 

 36.4 o/oo; pH, 7.85 to 8.25; phosphate, 15 to 138 mg 

 P04/m3. 



Peridinium claudicanoides thus appears to be a 

 rare, warm-water species possibly with a restricted 

 distribution. It will be noted that it occurred in a wide 

 range of salinities but never in the barren waters with 

 low phosphate content. If this correlation is correct, it 

 is an unusual feature for a tropical form. Type locali- 

 ty: Carnegie station 2. 



Peridinium oceanicum Vanhoffen 

 (Figure 30) 



Peridinium oceanicum Vanhoffen, 1897a, pi. 5, fig. 2. 

 Vanhoffen, 1897b, pp. 1-2. Jorgensen, 1905, p. 109. 

 Van Breeman, 1905, p. 44. Broch, 1906, pp. 154- 



156. Paulsen, 1907, p. 16, fig. 21. Paulsen, 1908, 

 pp. 39, 54. Meunier, 1910, p. 27. Broch, 1910, p. 

 190. Schroder, 1911, pp. 17-19, 21, 40. Mangin, 

 1913, p. 156. Paulsen, 1913, pp. 279-281, pi. 48. 

 Jorgensen, 1913, pp. 5-6. Meunier, 1919, pp. 15-19. 

 pi. 15, figs. 7-23, pi. 16, figs. 21-23. Paulsen, 1931, 

 p. 66, fig. 37, p. 55. Pavillard, 1931, pp. 56-57, 

 111, 125, 127, 129, 131, 133. 



Peridinium divergens . Stein, 1883, pi, 10, fig.7. 



Peridinium depressum var. oceanica , Ostenfeld, 1900, 

 p. 57, tables 2-7. Gran, 1902, p. 192. 



Peridinium divergens var. elegans Cleve, 1900b, p. 260. 

 Karsten, 1906, pp. 206, 209, 210, 213, 216,217,243, 

 245-247, 249, 257, 258, 260-261, 265-266,268, 272, 

 274-277, 279, 285, 287, 289, 293, 295r296, 298, 301, 

 311-312, 317-318, 328, 330-330,337,352-356, 416, 

 447, 450, 540. Karsten, 1907, p. 416. 



Peridinium depressa var. oceanica , Ostenfeld, 1900, tab.l 



Peridinium elegans var., Karsten, 1905, pp. 34, 132, pi. 

 19, figs. 5, 6. 



Peridinium elegans . Karsten, 1905, pp. 179, 208. 



Peridinium depressum oceanicum f . typica Broch, 1906, 

 p. 152. 



Peridinium oceanicum f. typica Broch, 1906, pp. 154- 



157, fig. 3. Broch, 1910, pp. 190-191. 

 Peridinium divergens oceanicum Karsten, 1907, p. 224, 



227, 228, 230-232, 257, 260-261, 272, 281,290, 416, 



447, 450, 472, 540. 

 Peridinium oceanicum var. typica Paulsen, 1908, p. 55, 



fig. 69. Mangin, 1913, p. 222. Lebour, 1925, p. 121. 

 Peridinium ozeanicum . Schroder, 1911, pp. 16, 25. 

 Peridinium murrayi var. occidentalis Pavillard, 1931, 



pp. 57, 114, 121, 147, 151, 153, 171, 181, 185, 187, 



189, fig. 9B, pi. 2. 

 Peridinium murrayi var. orientalis Matzenauer, 1933, 



p. 465, fig. 46b. 



Dimensions . Length of body (i) 246 (225-268) mi- 

 crons. Diameter of body (d) 124 (108-137) microns. 

 Width of girdle about 5 microns. Thirty-four specimens 

 measured. 



Shape . Body shape similar to P. depressum (seep. 

 16) but longer and more slender with relatively long 

 horns. The h/d ratio is 1.42 (1.27-1.68). The a/d ratio 

 is 0.58 (0.48-0.74). The b/a ratio is 0.12 (0.07-0.15). 

 The angle ais 119° (109-135°). 



