58 



OCEANIC TINTINNOINA OF LAST CRUISE OF CARNEGIE 



Rhabdonella exilis Kofoid and Campbell 

 RhabdoncUa exilis Kofoid and Campbell, 1929, p. 216, fig. 396. 



The very short lorica, with high oral rim, narrow conical 

 bowl, and pointed, prolonged peg-shaped horn, has a length 

 of 2.52 oral diameters. The oral rim is high and ringlike; 

 the suboral trough is plane, and angled out to the low outer 

 margin of the trough, the diameter of which is 1.09 oral 

 diameters. There is no suboral flare. The conical bowl 

 (10° to 15° in the upper part, increasing to as much as 45° 

 in the lower part) contracts evenly to the aboral end. The 

 aboral horn is nearly 0.5 oral diameter in length, peg-shaped, 

 and distally pointed. 



The wall is thickest suborally, gradually thinning in the 

 lower bowl. Laminae are evident only in the upper bowl, 

 those of the lower bowl being apparently fused. There are 

 46 left-directed (18°), weak, unbranched ribs which con- 

 tinue from end to end. Fenestrae are lacking. 



Length, 60 to 70^1. 



Rhabdonella exilis is shorter than R. cornucopia, and has 

 more ribs and also stouter proportions. The horn is better 

 developed than in R. indica. 



Recorded from twelve stations, three in the Atlantic and 

 nine in the Pacific, as follows: one (20) in the Sargasso Sea, 

 two (33, 34) in the Caribbean Sea, one (36) in the Pacific 

 equatorial region, three (63, 64, 65) in the South Pacific 

 middle latitudes, one (78) in the Galapagos region, two (91, 

 159) in the region of South Pacific island fields, one (140) 

 in the North Pacific trade region, and one (146) in the Cali- 

 fornia region. 



There are 10 pump and 3 net samples, of which 6 were 

 taken at the surface, 5 at 50 meters, and 2 at 100 meters. 

 Frequency, 3 per cent at station 65; 2 per cent at stations 36, 

 140, 146; average for Atlantic net samples, 1.6 per cent. 



Temperature : Atlantic, pump samples 26?05-28?5 1 ( 27? 28 ) , 

 net samples 23?i7-24?98 (24?07); Pacific, i5?90-28?65 

 (22?64) and 28?6o, respectively. Salinity: Atlantic, pump 

 samples 35-87-36.55 (36.21), net samples 36.49-36.53 (36.51); 

 Pacific, 31.62-36.03 (34.54) and 35.74, respectively. Density: 

 Adantic, pump samples 22.91-24. 21 (23.56), net samples 

 24.52-25.03 (24.77); Pacific, 20.34-25.43 (23.60) and 22.77, 

 respectively. pH: Atlantic, pump samples 8.28-8.37 (^-S^)) 

 net samples 8.18-8.21 (8.19); Pacific, 8.10-8.39 (8.19) and 

 8.37, respectively. 



Rhabdonella Hebe (Cleve) Brandt 

 Rhabdonella hebe, Kofoid and Campbell, 1929, p. 216, fig. 409. 



The moderately tall lorica, with moderate number of ribs, 

 conical bowl, and spindle-like swelling on the horn, has a 

 length of 4.15 oral diameters. The oral rim is very low, erect, 

 and ringlike, and the suboral trough which surrounds it is 

 concave; the outer margin has a diameter of 1.26 oral diam- 

 eters. The suboral flare (58°) is within o.i oral diameter 

 and forms a thickened suboral lip around the upper end of 

 the conical bowl. The bowl is subconical (20° in the anterior 

 0.37 total length and 36° in the lower 0.19). The aboral 

 horn is conical (8°), 0.44 total length in length, with a ten- 



dency toward the formation of a spindle near the distal end, 

 and with a minute, truncated, open ( .'' ) free tip. 



The wall is thickest across the suboral shelf, where it 

 reaches nearly 0.16 oral diameter; it becomes less than three- 

 tenths as much in the bowl. There are thin laminae which 

 enclose several layers of small, hexagonal prisms. Fenestrae 

 connect the laminae across the wall at intervals. There is a 

 curtain of jelly-like material enclosing the upper 0.24 of the 

 lorica. There are 11 to 28 left-deflected (5° to 7°), branched 

 ribs which die away on the suboral flare. Fenestrae are scat- 

 tered in I or 2 rows up and down each intercosta. The horn 

 is denser than the nearly transparent bowl. 



Length, 200 to 330[X. 



Rhabdonella hebe may be at once distinguished from R. 

 spiralis by shorter length, fewer ribs, proportions, and bowl 

 shape. Its horn is more distincdy set off from the bowl than 

 in R. valdestriata; it has fenestrae, lacking in R. chavesi, and 

 its oral region is narrower than in R. striata. It is not likely 

 to be confused with other species. 



Recorded from seven stations, three in the Atlantic and 

 four in the Pacific, as follows: one (15) in the Gulf Stream, 

 one (30) in the Atlantic equatorial region, one (31) in the 

 Caribbean Sea, one (45) in the Galapagos region, one (57) 

 in the South Pacific middle latitudes, one (145) in the North 

 Pacific middle latitudes, and one (146) in the California 

 region. 



There are 6 pump and 4 net samples, of which 3 were 

 taken at the surface, 3 at 50 meters, and 4 at 100 meters. 

 Maximum frequency, 72 per cent at station 15; other records 

 above minimum (6 to 12 per cent) from stations 145, 146 in 

 pump samples; average in Pacific pump samples, 24.6 loricae. 



Temperature: Atlantic, pumpsamples i8?56-i9?27(i8?9i), 

 net samples 22?56-27?88 (25?o8); Pacific, i6?58-22?37 

 (20?05) and 22'?37, respectively. Salinity: Atlantic, pump 

 samples 36.08-36.51 (36.32), net samples 36.45-36.47 (36.46); 

 Pacific, 34.32-34.91 (34.61) and 35.23, respectively. Den- 

 sity: Adantic, pump samples 26.12-26.26 (26.19), net samples 

 23.26-25.22 (24.31); Pacific, 23.88-24.66 (24.37) ^'^^ 24-3"> 

 respectively. pH: Atlantic, pump samples 8.19-8.21 (8.20), 

 net samples 8.19-8.30 (8.25); Pacific, 8.14-8.31 (8.26) and 

 8.13, respectively. 



Rhabdonella henseni (Brandt) Brandt 



(Figure 90) 



Rhabdonella henseni, Kofoid and Campbell, 1929, p. 216, fig. 

 408. 



The moderately elongated lorica, with wide, chalice-shaped 

 bowl, rather long, thick aboral horn, and vertical ribs, has a 

 length of 5.1 oral diameters. The oral rim is hyaline, higher 

 than the margin of the suboral trough, thin, ringlike, and 

 erect. The suboral trough is shallow, and its outer margin 

 has a diameter of 1.13 oral diameters. There is scarcely any 

 suboral flare. The bowl is subcylindrical for nearly 0.46 total 

 length, and convex conical (40°) for about i.i oral diam- 

 eters. The elongated, conical (8°) aboral horn has a basal 

 diameter of 0.3 oral diameter, and a length of almost 0.33 

 total length; its junction with the bowl is often asymmetrical. 



