CERATIUM SPECIES OF CARNEGIE COLLECTION 



33 



a surface form even when due correction is made for 

 contamination of the deeper net hauls. For Instance, it 

 was found in 25 per cent of the surface samples, but also 

 In 21 per cent of the 100-meter samples. 



37. Ceratium gibberimi Gourret 

 Figures 17D-G, chart 29, appendix table 34 



This Is a common, slightly tolerant tropical species 

 which occurs rather uniformly throughout the warm 

 waters of the world. Two varieties or subspecies are 

 usually recognized. One.f. dispar Pouchet (fig. 17D), 

 has a strongly curved right antapical horn and is com- 

 mon, whereas the other, f. subaeguale jSrgensen (fig. 

 17F), has regularly curved horns and is rare. The latter 

 was found by Peters (1934) in the South Atlantic in dif- 

 ferent regions, but it has not been reported before for 

 the Pacific. In the Carnegie collections one specimen of 

 this form was found (fig. 17F). This occurred off Japan at 

 station 114; depth, 50 meters; temperahireinsitu, 16.°2C. 



In f . dispar there is considerable variation in the 

 height of the epltheca, curvature of horn, and placement 

 of apical horn, but no further segregation of the group 

 could be made. The Pacific and Atlantic specimens ap- 

 peared to be identical. A two-celled chain was found at 

 station 48 at 100 meters (fig. 17E). 



The species was foiind at a total of 115 stations- -23 

 in the Atlantic and 92 in the Pacific. It was foimd at all 

 but three stations in the warm Atlantic region, but not 

 outside this region in the Atlantic (chart 29). In the Pa- 

 cific it was found almost continuously at the stations in 

 the warm Pacific region. It also occurred at ten stations 

 in the southeast Pacific region, but was absent from the 

 cold North Pacific region. 



The total number of sample records for the species 

 was 297, with 179 rare, 105 occasional, and 13 common. 

 Of the total number, 221 were net records and 76 were 

 pump records. 



The environmental conditions in situ were: temper- 

 ature, 14.°0 to 29.°3 C; salinity, 29.7 to 37.0 per mille; 

 pH, 7.17 to 8.47; phosphate, 2 to 178 mg P04/m3. 



Nielsen (1934) found that C. gibberimi had its main 

 vertical distribution above 50 meters. The Carneede 

 data show that the species occ\u"s more frequently in the 

 upper layers, with a decrease in frequency down to 100 

 meters (table 31). 



Table 31. Records of occurrence of C. gibberum 

 at three levels 



Rare 



Occasional 



Common 



Total 



75 



58 



7 



19.4 



15.0 



1.8 



56 



25 



4 



20.0 

 8.9 

 1.4 



48 



22 



2 



8.7 

 0.8 



140 



36.2 85 30.3 72 28.4 



A=Number of records. B=Per cent of total number of 

 samples collected at that depth. 



38. Ceratium concillans Jorgensen 

 Figures 17H-I, chart 30, appendix table 35 



This species was formerly included in C. gibberum 

 ijut was separated by Jorgensen (1920) and this separation 

 has been accepted by later workers (Peters, 1934; Niel- 



sen, 1934). Bohm (1931), however, figured C. gibberum 

 under the caption of C. concillans Jorgensen. 



Peters (1934) considered this species to be an indi- 

 cator of warm oligotrophic water in the South Atlantic. 

 Nielsen (1934), however, found that in the South Pacific 

 the species is found as much in eutrophlc oceanic water 

 as in oligotrophic oceanic water. It did, however, seem 

 to avoid neritic conditions. In the Carnegie collection in 

 the Pacific it was found in both eutrophlc and oligotroph- 

 ic water. This feature could not be considered for the 

 Atlantic as it was found at only one station there (in oli- 

 gotrophic water). On the Carnegie cnxise it was found in 

 eutrophlc water in the southeastern Pacific, again off 

 Peru, and off California. On the other hand, it occurred 

 in many waters poor in plankton and nutrients. Thus, 

 thirty of the seventy-five records of occurrence for the 

 species were in water containing less than 10 mg 

 P04/m3. It must be concluded that C. concilians is not 

 limited to one type of water. 



The species is not very common. In the Carnegie 

 collection it was found at a total of forty-two stations, 

 only one of which was in the Atlantic. The number of 

 sample records was seventy-five, of which fifty-nine 

 were rare, fourteen occasional, and two common. It is 

 much less common than its close relative, C. gibberum . 

 Since it is a fairly large form, it was found more fre- 

 quently in the net samples. There were forty-seven net 

 records and twenty-eight pump records. 



The range of surface temperatures for the species 

 is rather large for a tropical form, namely, from 16.°4 

 (station 128) to 29.°4 C (station 95). The ranges of en- 

 vironmental conditions in situ were: temperature, 12.°1 

 to 29.°3 C; salinity, 33.0 to 36.4 per mille; pH, 7.71 to 

 8.47; phosphate, ,3 to 198 mg P04/m3. 



Nielsen (1934) designated C. concilians as a surface 

 form. According to the Carnegie data, however, it is 

 found about equally at the surface, 50 meters, and 100 

 meters (see table 32). 



Table 32. Records of occurrence of C. concilians 

 at three levels 



Rare 



Occasional 



Common 



Total 



34 



7.8 



21 



7.4 



20 



7.9 



A=Number of records. B=Per cent of total number of 

 samples collected at that depth. 



A form was found at station 130 (fig. 171) which has 

 rather regular antapical horns and thus represents a va- 

 riety of C. concllans corresponding to var. subaeguale of 

 C. gibberum . 



39. Ceratium lunula Schlmper 

 Figures 17J-N, chart 31, appendix table 36 



Two forms of this species are commonly recognized; 

 f . brachvceros with short apical horn and comparatively 

 long antapicals; and f. magaceros with somewhat shorter 

 antapicals but with long apical horn. The latter form 



