TAXONOMY AND DISTRIBUTION 



35 



half); its least diameter, 0.88 oral diameter, is at the junction 

 of the upper and lower sections. At the neck the diameter 

 equals that of the oral rim. The bowl expands from the 

 throat to a diameter of 1.13 oral diameters at 0.54 total 

 length from the rim, the collar being 0.33 total length. The 

 lower bowl rounds off below the maximum diameter, and 

 the aboral end is blunt to rotund. 



The wall is extremely thin. The whole surface is fenes- 

 trated, with the upper windows squarish. The fenestrae of 

 the second row are smaller and more irregular, and the 

 fenestrae of the bowl are less uniform, 5 to 7 in vertical rows 

 and 10 to !2 in each horizontal row; at the aboral end is a 

 nest of tiny ones, and odd minute ones are scattered among 

 the larger ones of the bowl. All fenestrae are enclosed by 

 thickened beams and mullions, with a fine molding around 

 each window. All windows are closed by transparent panes. 



Length, 60 to 8ou. 



Hofker's ( 1 93 1 ) material appears typical although his 

 figures are generalized. 



Dictyocysta mitra is less stout and has a narrower aboral 

 end than D. obtusa. It has a less distinctly set-off and less 

 flaring collar region than D. dilatata (some of the Carnegie 

 loricae, as fig. 61, approach dilatata in this character), and 

 less acute aboral end. The fenestration differs markedly 

 from that of D. jenestrata, as does the general shape of the 

 bowl; in jenestrata the bowl is much less elongate. Dictyo- 

 cysta californiensis is smaller and has a greatly swollen bowl; 

 D. spinosa and D. extensa have oral spines lacking in mitra. 



Recorded from twenty-one stations, six in the Atlantic 

 and fifteen in the Pacific, as follows: two (2, 15) in the Gulf 

 Stream, three (3, 4, 5) in the Atlantic drift, one (23) in the 

 Atlantic equatorial region, four (42, 43, 44, 68) in the Gala- 

 pagos region, four (61, 63, 64, 65) in the South Pacific 

 middle latitudes, three (in, 128, 144) in the North Pacific 

 middle latitudes, and four (131, 133, 134, 135) in the Cali- 

 fornia region. 



There are 18 pump and 11 net samples, of which 1 was 

 taken at the surface, 9 at 50 meters, 18 at 100 meters, and 1 

 at 1000 meters. Maximum frequency, 6 per cent at station 

 65; other records above minimum (2 to 3 per cent) from 

 stations 3, 4, 44, 63, 64, in, 131; averages, 2.1 and 2.5 per 

 cent in Atlantic and Pacific net samples, respectively. 



Temperature: Atlantic, pump sample i8?56, net samples 

 i3? 7 9-20?35 (i5?o6); Pacific, 3 ? 9 8-i 5 ?o3 (n?36) and 

 io?23-i9?97 (i5?4o), respectively. Salinity: Atlantic, pump 

 sample 36.45, net samples 35.88-36.41 (36.02); Pacific, 33.07- 

 35.04 (34.46) and 33.36-35.04 (34.25), respectively. Density: 

 Atlantic, pump sample 26.26, net samples 25.76-27.01 (26.72); 

 Pacific, 24.64-26.19 (25.25) and 25.31-27.25 (26.04), respec- 

 tively. pH: Atlantic, pump sample 8.19, net samples 8.10- 

 8.21 (8.15); Pacific, 7.88-8.39 (8.15) and 7.76-8.32 (8.02), 

 respectively. 



Dictyocysta mulleri (Imhoff) Jorgensen emended Kofoid 



and Campbell 

 Dictyocysta midleri, Kofoid and Campbell, 1929, pp. 296-297, 



fig- 572- 

 The short lorica, with spool-shaped collar with double 



row of windows, and angled, aborally pointed bowl, has a 

 length of 1.51 oral diameters. The oral rim is undulating, 

 with 6 very fiat arches. The collar is spool-like, contracting 

 from the rim to 0.94 oral diameter near 0.48 oral diameter 

 from the rim, and then expanding to Ml oral diameters at 

 the neck, which is 0.81 oral diameter below the rim. There 

 is a double row of open windows, the upper row being ol 6 

 squarish ones, the lower being formed by 9 rounded rec- 

 tangles. The beams and mullions are thick and heavy-set. 

 The bowl is subcorneal (55 in the upper two-thirds, in- 

 creasing to 115° in the lower section). There is a rounded 

 but short shoulder below the collar, the maximum diameter 

 of which is 1.16 oral diameters. The aboral end is obtuse 

 and blunted. 



The wall of the bowl has an anterior row of 24 double, 

 circular fenestrae, and this row is followed by an incomplete 

 row of smaller circles. A row of 10 to 12 large, oval, post- 

 equatorial fenestrae adorns the bowl, and a lower row of 4 

 to 6 small windows is also present. The remaining surface 

 is covered with much smaller, relatively thick-walled fenes- 

 trae, although the area near the large fenestrae is free of tiny 

 circles. The fenestrae all have clear panes. 

 Length, 55 to 631.1. 



Dictyocysta mulleri differs from all other species in the 

 shape of the aboral end, which, combined with its wall char- 

 acters, differentiates it at once with little difficulty. Its 

 nearest relative is, possibly, D. magna, which not only is 

 longer, but also lacks the spool-like collar. Dictyocysta 

 ampla has a less angled bowl. 



Recorded from three stations, two in the Atlantic and one 

 in the Pacific, as follows: one (16) in the Gulf Stream, one 

 (20) in the Sargasso Sea, and one (82) in the region of 

 South Pacific island fields. 



There are 2 pump and 1 net sample, all taken at 100 

 meters. Frequency, minimum. 



Temperature: 19^62, 26^02, and 24?34 in the Atlantic 

 pump and net samples and Pacific pump sample, respectively. 

 Salinity: 36.48, 36.51, and 36.46 in the Atlantic pump and 

 net samples and Pacific pump sample, respectively. Density: 

 26.01, 24.19, and 24.65 in the Atlantic pump and net samples 

 and Pacific pump sample, respectively. pH: 8.17, 8.32, and 

 8.19 in the Atlantic pump and net samples and Pacific pump 

 sample, respectively. 



Dictyocysta nidulus Kofoid and Campbell 

 Dictyocysta nidulus Kofoid and Campbell, 1929, pp. 297-298, 



fig. 565. 

 The fairly tall lorica, with tiara-like fenestration and a 

 long bowl, has a length of 1.6 oral diameters. The oral 

 margin is simple and has a narrow list. The collar is 0.4 

 total length in length, virtually a cylinder, with a single row 

 of 7 rectangular (width 0.53 height) windows; in some indi- 

 viduals the windows, which are always open, have single, 

 somewhat oblique crossbars which subdivide them into two 

 more or less equal sections. The beams and mullions are 

 thin, rounded, and hyaline. The bowl is acorn-like in shape, 

 with some swelling a little below the collar (reaching 1. 1 

 oral diameters in diameter), and below it becomes angular 



