TAXONOMY AND DISTRIBUTION 



83 



Xystonellopsis dahli (Brandt) Kofoid and Campbell 



Xystonellopsis dahli, Kofoid and Campbell, 1929, p. 245, fig. 

 483. 



The rather elongated lorica, with little-differentiated aboral 

 region and without a skirt, has a length of 6.15 oral diam- 

 eters. The oral margin is thin and barely spread. The long 

 bowl is subcylindrical in the upper three-fifths, and sub- 

 conical (23 ) below. The pedicel is subcylindrical, 0.19 total 

 length in length, and without a skirt. The lance is short, 

 conical (2 ), 0.54 oral diameter in length, and sharply 

 pointed at the free tip. 



The wall has a thickness of nearly 0.08 oral diameter; it 

 has thin laminae and enclosed fine hexagons; the outer sur- 

 face is almost clear, but there are 6 subvertical lists on the 

 pedicel. 



Length, 396 to 444U. 



Xystonellopsis dahli is shorter, with less aboral concavity 

 and less aboral differentiation than X. \rammeri. It has no 

 skirt as do X. tenuirostris and related species. 



Recorded from one station (95) in the region of South 

 Pacific island fields, in 1 pump and 1 net sample, both taken 

 at 100 meters. Frequency, 2 per cent. 



Temperature, 28^74; salinity, 35.35; density, 22.43; P H > 

 8.22. 



Xystonellopsis dicymatica (Brandt) Kofoid and Campbell 



Xystonellopsis dicymatica, Kofoid and Campbell, 1929, p. 245 

 (for fig. 467 see X. inaequalis). 



The moderately tall lorica, with two wide, equal rings 

 marking the ends of a suboral spool, and with conical bowl, 

 thin pedicel, and narrow lance, has a length of 5.7 oral diam- 

 eters. The oral margin is thin and erect. The thickened 

 suboral spool occupies the anterior oral diameter. Just below 

 the oral rim is the upper ring, with a diameter of 1.4 oral 

 diameters; the lower one has a diameter not exceeding 1.5 

 oral diameters. The diameter of the bowl midway between 

 the rings is 1.3 oral diameters. The bowl below the spool 

 contracts conically (16 in the anterior 0.23 and 20° in the 

 posterior 0.28 total length). The pedicel is very thin (less 

 than 0.2 oral diameter at the most) and fairly short (0.29 

 total length), and has an expanded, aborally truncated skirt. 

 The lance is conical (2°), 0.6 oral diameter in length, and 

 sharply pointed. 



The wall has a thickness of not over 0.1 oral diameter in 

 the lower bowl. There are thin laminae, which enclose 

 several layers of small hexagons in the spool and a single 

 layer of radial rectangles in the lower bowl; in the skirt 

 region there are several layers of tiny alveoles. The lumen 

 does not enter the rings and in the lance is reduced to a fine 

 canal. 



Length, 250 to 280U. 



Kofoid and Campbell (1929, fig. 467) have a lorica with 

 a wide lower ring nearly 1.6 oral diameters across. This 

 specimen is better assigned to Xystonellopsis inaequalis, 

 though the ring is not saucer-shaped as in the usual in- 

 aequalis. 



Xystonellopsis dicymatica differs from X. inaequalis in 

 having the two rings subequal. U has 2 rings, whereas X. 

 cymatica has but one, anil A', abbreviata has three. 



Recorded from nineteen stations, ten in the Atlantic and 

 nine in the Pacific, as follows: one (19) in the Sargasso Sea, 

 five (22, 23, 24, 27, 28) in the Atlantic equatorial region, 

 four (31, 32, 33, 34) in the Caribbean Sua, two (35, 154) in 

 the Pacific equatorial region, two (1.1, (17) in the South 

 Pacific middle latitudes, two (68, ~^) in the Galapagos 

 region, one (u$) in the North Pacific middle latitudes, and 

 two (147, 148) in the California region. 



There are 1 pump and 21 net samples, oi which 5 were 

 taken at 50 meters and 17 at 100 meters. Maximum fre- 

 quency, 15 per cent at station 19; other records above mini- 

 mum (2 to 15 per cent) from stations 19, 28, 32, 33, 35, 61, 

 67, 148, 154; averages in net samples, 2.9 and 4.0 per cent in 

 the Atlantic and Pacific, respectively. 



Temperature: Atlantic, net samples i7?34~26?79 (22^32); 

 Pacific, pump sample 21 "74, net samples io?92-25?8i 

 (i7?96). Salinity: Atlantic, net samples 36.00-37.05 (36.34); 

 Pacific, pump sample 34.66, net samples 34.05-35.47 (34.84). 

 Density: Atlantic, net samples 23.98-26.29 (25.15); Pacific, 

 pump sample 24.06, net samples 22.98-26.06 (25.11). pH: 

 Atlantic, net samples 7.99-8.30 (8.17); Pacific, pump sample 

 8.23, net samples 7.92-8.39 (8.07). 



Xystonellopsis favata (Brandt) Jorgensen 



Xystonellopsis favata, Kofoid and Campbell, 1929, p. 240, fig. 

 477- 



The fairly elongated lorica, with wide bowl, short pedicel, 

 and lance, has a length of 4.0 oral diameters. The oral margin 

 is thin and erect. The bowl swells within the anterior 0.3 

 oral diameter to 1.08 oral diameters and then contracts (21 °) 

 for 0.5 oral diameter, forming, within the upper region, a 

 thickened section. Below this thick region the bowl is sub- 

 conical (8° in the anterior 1.25 oral diameters and 33 in 

 the lower 1.0). The pedicel is short (0.75 oral diameter), 

 tubular, and squarely truncated aborally. From its lower 

 end arises the conical (io°) lance, the length of which is 

 0.42 oral diameter; its distal tip is sharply pointed. 



The wall averages approximately 0.08 oral diameter in 

 thickness in the bowl. There are thin laminae, enclosing 

 several layers of extremely faint, minute alveoles. The 

 lumen follows the contour of the bowl, but in the pedicel it 

 forms a narrow canal which continues to the tip of the lance. 

 On the pedicel are 12 subvertical lines or folds. 



Length, 220 to 290(1. 



Xystonellopsis favata resembles X. scyphium save that its 

 bowl is relatively longer and narrower, and its pedicel is less 

 set off from the bowl. It is not distant from X. tenuirostris, 

 but its bowl is relatively wider, with more aboral taper, and 

 the pedicel is not so stout or so long. 



Recorded from one station (75) in the Galapagos region, 

 in a net sample taken at 100 meters. Frequency, 3 per cent. 



Temperature, i8?40; salinity, 35.47; density, 25.55; pH, 

 8.10. 



