TAXONOMY AND DISTRIBUTION 



layered, secondary rectangles, and within these are minute- 

 alveoles in several layers. On the surface are 20 to 28 sub- 

 vertical ribs, which continue down the pedicel and over the 

 skirt. The areas between the ribs are free of fenestrae. The 

 suboral ring and the lance are hyaline, but the pedicel is 

 brownish. 



Length, 297".. 



The ribs are less deflected and the lorica is shorter than 

 in specimens from other sources. 



Rhabdonellopsis apophysata has more ribs than R. longi- 

 caulis, which species not only is longer, but also is fenestrate 

 and has a heavier knob. Rhabdonellopsis composita lacks 

 ribs on the knob, and has fewer ribs on the bowl. Rhabdo- 

 nellopsis intermedia is shorter, is fenestrate, and has fewer 

 ribs. In the remaining species the knob is spindle-like. 



Recorded from nine stations, seven in the Atlantic and 

 two in the Pacific, as follows: two (19, 20) in the Sargasso 

 Sea, two (27, 29) in the Atlantic equatorial region, three 

 (31, 32, 34) in the Caribbean Sea, and two (35-36, 37) in the 

 Pacific equatorial region. 



There are 12 net samples, of which 3 were taken at the 

 surface, 3 at 50 meters, and 6 at 100 meters. Maximum fre- 

 quency, 10 per cent at station 32; other records above mini- 

 mum (2 to 8 per cent) from stations 27, 32, 34, 35-36; aver- 

 ages, Atlantic 4.3 per cent, Pacific 3.8 per cent. 



Temperature: Atlantic, i8?o8-26?04 (24?8i); Pacific, 

 1 record only, 27? 12. Salinity: Atlantic, 36.03-37.15 (36.57); 

 Pacific, 31.68. Density: Atlantic, 23.98-26.06 (25.52); Pacific, 

 20.20. pH: Atlantic, 8.09-8.30 (8.20); Pacific, 8.28. 



Rhabdonellopsis composita (Brandt) Kofoid and Campbell 



(Figure 87) 



Rhabdonellopsis composita, Kofoid and Campbell, 1929, pp. 

 222-223, fig. 421. 



The rather tall lorica, without ribs on the pedicel, and 

 with few ribs, stout knob, and thick lance, has a length of 

 6.05 oral diameters. The oral margin is erect, thin, ringlike, 

 and higher than the outer edge of the suboral trough. The 

 suboral trough is concave and the diameter of its rounded- 

 over outer rim is 1.17 oral diameters. The bowl flares (73 ) 

 within the anterior fifth. Below the flare it tapers (8°) for 

 0.28 total length, and then becomes subconical (26 ) for 

 nearly 0.23 total length. The long pedicel is a cylinder (0.25 

 oral diameter in diameter) with a length of almost 0.42 total 

 length. At its lower end is the thickened, skirtlike knob. 

 From the middle of the knob arises the thick lance (0.6 oral 

 diameter in length). 



The wall reaches a maximum thickness of 0.14 oral diam- 

 eter at the flare and thins down to a tenth that much in the 

 bowl. There are thin laminae which enclose minute alveoles. 

 There are 12 vertical, unbranched ribs, which die out below 

 the middle of the bowl, so that the lower half is nonstriate. 

 A few (2 to 6) minute fenestrae are found scattered along 

 each intercosta. The lance has vertical fins. The whole 

 lorica is colorless, save the knob. 



Length, 280 to 353U. 



Rhabdonellopsis composita has fewer ribs of shorter length 



63 



than R. apophysata; it is also fenestrated, and the lance is 

 fluted. 



Recorded from sixteen stations in the Atlantic, as follows: 

 two (15, 16) in the Gulf Stream, six (17, 18, 19, 20, 20-21, 

 21) in the Sargasso Sea, seven (22, 23, 24, 26, 27, 28, 29) in 

 the Atlantic equatorial region, and one (34) in the Carib- 

 bean Sea. 



There are 17 pump and 17 net samples, of which 14 were 

 taken at the surface, 11 at 50 meters, and 9 at 100 meters. 

 Maximum frequency, 16 per cent at stations 15, 24; other 

 records above minimum (2 to 5 per cent) from stations 18, 

 19, 21; average in net samples, 5.1 per cent; pump samples, 

 140 loricae taken at station 15, 33 at station 27, 12 at station 

 34, and 13 at station 24. 



Temperature: pump samples i7?5o-28?5i (24?62), net 

 samples i5?55-26?98 (22^65). Salinity: pump samples 

 35.22-37.15 (35-54). net samples 35.61-37.15 (36.44). Den- 

 sity: pump samples 22.84-26.26 (24.20), net samples 23.79- 

 26.34 ( 2 4-9 2 )- pH: pump samples 8.14-8.37 (8.26), net 

 samples 7.96-8.32 (8.27). 



Rhabdonellopsis intermedia Kofoid and Campbell 



Rhabdonellopsis intermedia Kofoid and Campbell, 1929, p. 223, 

 fig. 424; Marshall, 1934, pp. 650-651, fig. 28. 



The short lorica, with flaring conical bowl, tapering shatt, 

 and deflected ribs, has a length of 4.9 oral diameters. The 

 oral rim is low and ringlike, and forms the inner boundary 

 of the concave suboral trough. The diameter of the trough 

 is 1. 14 oral diameters. The bowl flares (63 ) within the 

 upper 0.1 oral diameter, then tapers (12°) for 0.31 total 

 length, and finally becomes inverted subconical (38 ) for 

 0.8 oral diameter. The pedicel also tapers (8°), the transi- 

 tion between the lowermost section of the bowl and the 

 pedicel being gradual. The pedicel also expands a bit above 

 the knob, so that it is distinctly concave in lateral contour; 

 it has a length of nearly 0.33 total length. At its lower end 

 is the modestly expanded knob, from the middle of which 

 arises the lance (0.5 oral diameter in length), the free tip oi 

 which is sometimes open. 



The wall has a thickness of 0.15 oral diameter suborally 

 and thins down evenly in the lower bowl. There are thin 

 laminae which enclose radial, rectangular secondary prisms, 

 which in their turn enclose minute alveoles in several layers. 

 The ribs number 16 (24); they are deflected (up to io°) to 

 the left, and sometimes they branch. They continue on the 

 pedicel, knob, and lance. The intercostae have 7 to 16 small 

 fenestrae and strongly developed, though small, prisms. 



Length, 222 to 2gS\l. 



Rhabdonellopsis intermedia is shorter than R. apophysata, 

 with fenestrae and fewer ribs. The ribs are continued the 

 whole length, whereas in R. composita they die out on the 

 bowl. The pedicel is relatively shorter, as is the whole lorica 

 actually, than in R. longicaulis. 



Recorded from six stations in the Pacific, as follows: two 

 (45, 46) in the Galapagos region, two (83, 84) in the region 

 of South Pacific island fields, and two (100, 150) in the 

 North Pacific trade region. 



