TAXONOMY AND DISTRIBUTION 



91 



lower end of this section is 0.85 oral diameter. The lower 

 section of the bowl is inverted conical (47°), and its length 

 is a little more than 0.33 total length. The lance is about as 

 long as the section above it, and it tapers (12 ) to the 

 sharply pointed free tip. 



The hyaline wall has a maximum thickness of 0.15 oral 

 diameter within the upper one-fifth, the lower bowl and 

 lance having a wall thickness of less than a third as much. 



Length, 89 to tl3(l. 



Parundella praetenuis differs from P. difficilis in its rela- 

 tively shorter bowl and longer lance; it is actually also 

 shorter. Parundella humerosa is longer, with greater sub- 

 oral bulge and stouter horn; this is also true of P. caudata 

 and P. gigantea. 



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

 (75) in the Galapagos region and one (in) in the North 

 Pacific middle latitudes. 



There are 1 pump and 1 net sample, of which 1 each was 

 taken at 50 and 100 meters. Frequency, 9 per cent in the net 

 sample. 



Temperature: net sample 18^40, pump sample 19^39. 

 Salinity: net sample 35.47, pump sample 34.58. Density: 

 net sample 25.55, pump sample 24.62. pH: net sample 8.10, 

 pump sample 8.18. 



XYSTONELLA Brandt emended 



Xystonella, Kofoid and Campbell, 1929, p. 234. 



The presence of a suboral trough distinguishes this genus 

 from Xystonellopsis and marks it as more advanced in oral 

 characters; in the Tintinnoina the suboral region and the 

 aboral section afford the most distinctive characteristics. 

 Xystondla is no exception. Wall characters are virtually 

 the same as in other genera of the family. 



Xystonella, though more advanced in oral characters, is 

 not especially abundant either in kind or in number. As a 

 whole the species seem to prefer somewhat cooler waters 

 than do those of Xystonellopsis, but not the icy arctic oceans. 

 One species, Xystonella trejorti, is likely to be found almost 

 anywhere in warm oceanic waters. 



Eight species are described here, of which two are new. 



Xystonella acus (Brandt) Brandt 



Xystonella acus, Kofoid and Campbell, 1929, p. 234, fig. 447. 



The short, chalice-shaped lorica, with long, spindle-like 

 lance, has a length of 4.2 oral diameters. The thin oral rim 

 is erect and scarcely developed. The suboral trough is almost 

 flat, and its outer rim has a diameter of 1.1 oral diameters. 

 The bowl flares (21°) within the anterior 0.67 oral diameter; 

 the diameter at the lower end of the flare is similar to the 

 length. Below this level the bowl gradually contracts until 

 it reaches 0.55 oral diameter at 1.33 oral diameters below the 

 rim, and then expands to 0.67 oral diameter at 2.0 oral diam- 

 eters. Below this last level it is conical (33°) for 1.22 oral 

 diameters. The lance is contracted in its middle and swells 

 to a narrow lancet-shaped extension toward the distal end; 

 the free tip is sharp. The lance has a length of little more 

 than 0.31 total length. 



The wall is uniformly approximately 0.07 oral diameter 

 in thickness, and there are laminae which enclose secondary 

 prisms. The surface is covered by a fine, pallid hexagonal 

 mesh. 



Length, 19011. 



Xystonella acus has a spindle-like lance, whereas X. lanceo- 

 lata has a tubular one and X. longicauda has a needle-like 

 one, as does also the much longer X. lohmanni. Xystonella 

 curticauda and X. flemingi have relatively shorter lances, of 

 different form. 



Recorded from six stations, one in the Atlantic and five in 

 the Pacific, as follows: one (5) in the Atlantic drift, two (51, 

 65) in the South Pacific middle latitudes, one (78) in the 

 Galapagos region, one (113) in the North Pacific middle 

 latitudes, and one (135) in the California region. 



There are 3 pump and 3 net samples, of which 2 were 

 taken at the surface and 4 at 100 meters. Maximum fre- 

 quency, 4 per cent at station 113; other records minimum; 

 average in Pacific net samples, 2.5 per cent. 



Temperature: Atlantic, net sample 13^51; Pacific, pump 

 samples 2o?o7~24?55 (22^79), net samples i5?23~2i?74 

 (i8?48). Salinity: Atlantic, net sample 35.90; Pacific, pump 

 samples 35.12-35.95 (35.56), net samples 34.30-34.66 (34.48). 

 Density: Atlantic, net sample 27.00; Pacific, pump samples 

 23.83-25.24 (24.42), net samples 24.06-25.44 (24.75). pH: 

 Adantic, net sample 8.15; Pacific, pump samples 8.17-8.37 

 (8.25), net samples 8.10-8.23 (8.16). 



Xystonella clavata Jorgensen 



Xystonella clavata, Kofoid and Campbell, 1929, pp. 235-236, 

 fig. 450. 



The narrow, elongate lorica, with lancet-shaped expan- 

 sion at the end of the lance, has a length of 8.2 oral diam- 

 eters. The thin oral rim is a low, erect cuff, not visible in 

 side view by reason of the elevation of the outer rim of the 

 suboral trough. The outer rim has a diameter of 1.27 oral 

 diameters, and its free edge is separated from the cuff by a 

 very shallow, concave trough. The long bowl flares (25 ) 

 within the anterior 1.0 oral diameter, the diameter of this 

 region at the lower end of the flare being 0.86 oral diameter. 

 Below the lower end of the flare the bowl swells to 0.8 oral 

 diameter at 2.26 oral diameters below the rim; the swollen 

 region occupies about 1.53 oral diameters. The lower bowl 

 tapers (14°) for 2.13 oral diameters and then becomes a 

 narrow (0.15 oral diameter) tube with a length of nearly 

 0.28 total length. At the end of this tubular section is the 

 lance-shaped, flat (?), angular expansion which distinguishes 

 the species; it has a length of 1.0 oral diameter and a width 

 of 0.2 its length. 



The wall has a maximum thickness of 0.14 oral diameter 

 just below the trough; it gradually thins to less than 0.02 

 lower down. There are thin laminae which enclose sub- 

 equal, rectangular, radial secondary prisms, which in their 

 turn enclose minute alveoles. The surface has a meshwork 

 of small hexagons. The aboral expansion is dense and 

 brown, but the rest of the lorica is glassy. 



Length, 242 to 350U.. 



