CERATIUM SPECIES OF CARNEGIE COLLECTION 



39 



of the genus. It is a very tolerant tropical species which 

 may be displaced by currents. It was found at a total of 

 152 stations--28 in the Atlantic and 124 in the Pacific. 

 In the Atlantic it was found at practically every station 

 in the warm Atlantic region and at three stations in the 

 cold Atlantic region, the most northern of these being 

 station 6c off Ireland where the surface temperature was 

 12.°4 C. In the Pacific it occurred almost continuously 

 throughout the warm Pacific and southeast Pacific re- 

 gions. It extended northward at either side of the Pacif- 

 ic, somewhat beyond the limits of this region: off Japan 

 to station 116 where the surface temperature was 16.°1 

 C; and off the United States to station 128, surface tem- 

 perature 16.°4 C. In the southeastern Pacific itoccurred 

 at the southernmost station, station 60, where the sur- 

 face temperature was 15.°0 C. 



The environmental conditions in situ were: temper- 

 ature, 10.°6 to 29°5 C; salinity, 29.7 to 37.0 per mille; 

 pH, 7.17 to 8.47; phosphate, 2 to 233 mg P04/m3. 



Of the 476 records, 194 were from water containing 

 less than 10 mg P04/m3. 



The species is quite common, as shown by the num- 

 ber of sample records which totaled 479. Of these, 159 

 were rare, 210 occasional, 102 common, and 8 abundant. 

 Net samples predominated, with 348 records as against 

 131 pump records. The large number of net records 

 doubtless was owing to the large spread of the horns 

 which made the capture of this species efficient in the 

 coarser cloth of the tow net. 



Nielsen (1934) classified C. massiliense as a sur- 

 face species. The Carnegie data corroborate this (table 

 40). The species was found with decreasing frequency 

 with increase in depth although the decrease was not great. 



Table 40. 



Records of occurrence of C. massiliense 

 at three levels 



Rare 



Occasional 

 Common 

 Abundant 



Total 



65 



96 



55 



5 



16.9 



24.9 



14.3 



1.3 



45 



65 



31 



2 



15.6 



22.3 



11.0 



0.7 



49 



49 



16 



1 



18.9 



19.3 



6.3 



0.4 



221 



57.4 143 49.6 115 44.9 



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

 samples collected at that depth. 



48. Ceratlum deflexum (Kofoid) Jorgensen 

 Figures 22C-D, chart 39, appendix table 44 



Ceratlum deflexum is an intolerant tropical species, 

 probably restricted to the Pacific and Indian oceans. 

 Peters (1934), in his study of the material of the Meteor 

 from the South Atlantic, included C. deflexum as a vari- 

 ation of C. massiliense. Unfortunately, he did not give a 

 figure of it. Undoubtedly it was the variety mentioned 

 above (p. 38, fig. 22H), which is a variant of C. massiliense 

 but is not to be identified with C. deflexum. Ceratlum 

 deflexum is characterized by a ventral curvature of the 

 antapical horns (fig. 22D) which is not found in any of the 

 variants of C. massiliense . In addition to this, the pos- 

 terior extension of the horns is much greater than in C^ 

 massiliense. Ceratlum deflexum is a distinctive species 

 and is easily recognized after it has been observed once. 



In the Carnegie collection it was found at fifty-three 

 stations--all in the Pacific. There were 105 records of 

 occurrence, of which 58 were rare, 34 occasional, and 

 13 common. Eighty-four were from net records and 21 

 were from pump records. 



Most of the stations were concentrated in the east- 

 ern and central Pacific between latitudes 20° north and 

 20° south, except for one station at Japan and two sta- 

 tions in the southern part of the southeast Pacific region. 

 The species probably is not as limited in its distribution 

 as the Carnegie data indicate, since it was found off San 

 Diego, California by Kofoid (1907a), in the China Sea 

 south of 20° north latitude by Bohm (1931), and in the 

 Indian Ocean by Jorgensen (1911). 



The species was found only at stations with high 

 temperatures, except at the two stations to the southeast. 

 The surface temperatures at the main group of stations 

 ranged from 18.°7 to 29.°3 C; at the two stations in the 

 southeast, 16.°9 and 19.°2 C. The ranges of environmen- 

 tal conditions in situ were: temperature, 10.°8 to 29.°3C; 

 salinity, 29.7 to 36.5 per mille; pH, 7.82 to 8.47; phos- 

 phate, 4 to 166 mg P04/m3. 



The curious distribution of this species may be ow- 

 ing to a preference for eutrophic water. In the large 

 oligotrophlc area of the North Pacific, where the average 

 phosphate content of the upper 50 meters was less than 

 10 mg P04/m3, there were only nine stations. Its ab- 

 sence off Peru might be attributed, then, to lower tem- 

 peratures, and its absence in the Easter Island region to 

 oligotrophlc conditions. The greatest number of stations 

 were in the regions where the average phosphate content 

 was above 25 mg and the greatest populations were found 

 at stations where the phosphate content was above 25 or 

 50 mg P04/m3. In this connection it is to be noted that 

 of the 107 sample records for the species, only 11 were 

 in water containing less than 10 mg P04/m3. 



The species is a surface form. In the Carnegie col- 

 lection it was found with decreasing frequency with in- 

 crease in depth (see table 41). Thus, it was found in 15.5 

 per cent of the surface samples and only 6.7 per cent of 

 the 100-meter samples. Because of contamination of the 

 deeper hauls, the real distribution is probably even more 

 definitely a surface one than the present data indicate. 



Table 41. 



Records of occurrence of C. deflexum 

 at three levels 



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

 samples collected at that depth. 



49. Ceratlum carriense Gourret 

 Figure 22A, chart 40, appendix table 45 



This is a rather variable species of uncertain taxo- 

 nomic position. Certain varieties have been named which 

 show characteristic spread of horns (for instance, var. 

 volans Cleve and f. cevlonicum SchrSder), but in the 



