56 



OCEANIC TINTINNOINA OF LAST CRUISE OF CARNEGIE 



faintness of fenestrae. They may, however, not be Rhab- 

 donella amor, but rather a new species peculiar to the Barrier 

 Reef. 



Rlnil'donella amor averages fewer ribs than R. indica, is 

 longer, and lacks pronounced suboral Hare. It lacks the peg 

 of the somewhat longer R. cornucopia and the distinct horn 

 of the shorter R. exilis. It is easy to distinguish it from other 

 species. 



Recorded from thirty-four stations, sixteen in the Atlantic 

 and eighteen in the Pacific, as follows: one (15) in the Gulf 

 Stream, two (19, 21) in the Sargasso Sea, nine (21-22, 22, 23, 

 24, 25, 27, 28, 29, 30) in the Atlantic equatorial region, four 

 (31, 32, 33, 34) in the Caribbean Sea, four (35, 35-36, 36, 39) 

 in the Pacific equatorial region, two (60, 62-63) in the South 

 Pacific middle latitudes, two (73, 80) in the Galapagos 

 region, six (81, 82, 85, 93, 96, 160) in the region of South 

 Pacific island fields, one (144) in the North Pacific middle 

 latitudes, one (146) in the California region, and two (150, 

 151) in the North Pacific trade region. 



There are 19 pump and 41 net samples, of which 25 were 

 taken at the surface, 18 at 50 meters, and 17 at 100 meters. 

 In general this species has a pronounced surface preference. 

 Maximum frequency, 30 per cent at station 30; other records 

 above minimum (2 to 12 per cent) from stations 21-22, 22, 

 24, 25, 27, 29, 31, 32, 33, 34, 35, 35-36, 60, 80, 82, 85, 151, 160; 

 averages in net samples, 2.0 and 3.8 per cent for the Atlantic 

 and Pacific, respectively; the pump samples include from 1 

 to 15 loricae, with averages of 1.7 and 5.0 in the Atlantic and 

 Pacific, respectively. 



Temperature: Atlantic, pump samples i4?6o-28?5i (23^59), 

 net samples i4?6o-27?88 (22^82); Pacific, i7? 4 6-2 9 ?3o 

 (24?39) and i4?97~28?58 (24^39), respectively. Salinity: 

 Atlantic, pump samples 35.22-36.99 (35.99), net samples 

 35.61-37.15 (36.29); Pacific, 34.59-35.42 (35-07) and 31.62- 

 36.33 (34.83), respectively. Density: Atlantic, pump samples 

 22.73-26.62 (23.77), net samples 23.26-26.34 (24.84); Pacific, 

 21.95-25. n (23.58) and 20.34-25.60 (23.33), respectively. 

 pH: Atlantic, pump samples 7.93-8.34 (8.31), net samples 

 7.93-8.31 (8.23); Pacific, 8.12-8.37 (8- 22 ) and 7.92-8.44 

 (8.23), respectively. 



Rhabdonella brandti Kofoid and Campbell 



(Figure 89) 



Rhabdonella brandti Kofoid and Campbell, 1929, p. 213, fig. 

 400; Marshall, 1934, p. 649, fig. 24. 



The short, chalice-shaped lorica, with tapering conical bowl 

 and fairly long horn, has a length of 3.42 oral diameters. 

 The oral rim is thin and erect, and its outer edge is the con- 

 cave upper margin of the inner face of the suboral trough. 

 The suboral trough is flattened toward the periphery, and 

 the diameter of its outer margin is 1.23 oral diameters. There 

 is some suboral flare (28°) within the anterior 0.3 oral diam- 

 eter. The bowl tapers (10°) for about 0.4 total length, then 

 becomes inverted subconical (33°) for approximately another 

 0.4. The aboral horn is narrow conical (13°), about 1 oral 

 diameter in length, and with a basal diameter of 0.23 oral 

 diameter. The free tip is sharply pointed. 



The wall is thickest suborally (nearly 0.16 oral diameter) 

 and becomes gradually thinner lower down. There are thin 

 laminae which enclose minute alveoles. There are 48 long, 

 vertical, sometimes anastomosed ribs with 26 to 34 minute, 

 distinct fenestrae in each intercostal space. Minute alveoles 

 are externally evident in the generally brownish wall. 



Length, 95 to 198(1. 



This distinctive species has less suboral flare, less wide 

 bowl, and more irregular ribs than R. elegans. Its horn is 

 not so long or so narrow as that of R. quantula or R. inflata. 



Recorded from four stations in the Atlantic, as follows: 

 two (15, 16) in the Gulf Stream, and two (19, 20) in the 

 Sargasso Sea. 



There are 1 pump and 5 net samples, ot which 2 were 

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

 Frequency, 2 per cent at station 19; 15 loricae in pump 

 sample at station 16; average for net samples, 1.6 per cent. 



Temperature: pump sample 25^92, net samples 22^42- 

 24?8i (23?28). Salinity: pump sample 36.16, net samples 

 36.39-37.07 (36.73). Density: pump sample 23.93, net 

 samples 24.47-25.67 (25.17). pH: pump sample 8.24, net 

 samples 8.19-8.26 (8.22). 



Rhabdonella conica Kofoiil and Campbell 



Rhabdonella conica Kofoid and Campbell, 1029. pp. 214-215, 

 fig. 418. 



The very tall, lanky lorica, with conical bowl, greatly 

 elongated horn, and little transition between bowl and horn, 

 has a length of 6.5 oral diameters. The oral rim is sub- 

 merged and recurved. The suboral trough is asymmetrically 

 concave; the diameter of its outer margin is 1.1 oral diam- 

 eters. The narrow bowl tapers (8°), but has a more or less 

 ringlike suboral swelling, its length being approximately 0.5 

 total length. The long aboral horn continues with the same 

 taper, although this is gradually reduced to less than 6° near 

 the tip. 



The wall is only 0.03 oral diameter in thickness at the 

 thickest part. There is a suboral jelly-like curtain in some 

 individuals, in the anterior three-tenths or less. The laminae 

 are very thin and enclose extremely minute alveoles. There 

 are 48 left-deflected, often branched, and sometimes anasto- 

 mosed ribs. The intercostae have a dozen or more rather 

 large, oval, subequidistant fenestrae and a fine mesh work of 

 tiny hexagons. 



Length, 290 to 480(1. 



Some loricae reach 8.0 oral diameters in length, and the 

 aboral horn is often nearly transparent; mostly the loricae 

 are brown. 



Because of its length and thinness, Rhabdonella conica is 

 easy to distinguish. In form it resembles R. aberrans, but 

 that species is shorter, with an irregular oral region and de- 

 fective ribs. Rhabdonella cuspidata is inflated in the lower 

 bowl and of stouter fades although about as long as conica. 

 The horn is always relatively longer in R. conica than in 

 R. spiralis, and there is almost no transition between bowl 

 and horn in conica; this character is rather distinct in spiralis. 



Recorded from seventeen stations, one in the Atlantic and 



