TAXONOMY AND DISTRIBUTION 



79 



variation, may be compared with P. pacifica, from which it 

 differs in the more tapering aboral end and lack of horn; 

 from P. obtusangida it differs in aboral characters. 



Recorded from seven adjacent stations in the Atlantic, as 

 follows: one (7) in the North Sea, four (8, 9, 10, 11) in the 

 Atlantic drift, and two (12, 13) in the American cold-water 

 region. 



There are 3 pump and 17 net samples, of which 7 were 

 taken at the surface, 8 at 50 meters, and 5 at 100 meters. 

 Maximum frequency, 100 per cent at station 8 at 100 meters, 

 station 11 at the surface, station 12 at 100 meters, and station 

 13 at 50 meters; all other records 2 to 99 per cent. 



Temperature: pump samples 7?oi-i4?47 (ii?27), net 

 samples i?64-ii?27 (7?9i). Salinity: pump samples 32.68- 

 34.97 (34.18), net samples 33.40-35.25 (34.82). Density: 

 pump samples 24.94-27.42 (26.38), net samples 24. 94-27. 96 

 (27.14). pH: pump samples 7.92-8.06 (7.99), net samples 

 7.93-8.08 (7.98). 



Parafavella promissa Hada 

 Pnnifai'clla promissa Hada, 1932(7, p. 53, fig. 18. 



The elongated, narrow lorica, with sharply recurved oral 

 teeth, cylindrical bowl, and very long, spinelike aboral horn, 

 has a length of 7.3 oral diameters. The oral margin flares 

 very slightly, and there are 24 subequidistant, narrow, de- 

 cidedly outward-flaring, triangular teeth. The long upper 

 bowl is a cylinder expanded a bit near the upper end, and 

 occupies 2.56 oral diameters. The aboral convex-conical 

 (45°) section has a length of nearly i.o oral diameter. The 

 very elongated aboral horn is conical (not over 2°) and is 

 about 0.5 or more of the total length. At its free tip there 

 is sometimes a minute disk-shaped expansion. 



The wall has a thickness of 0.06 oral diameter in the bowl, 

 a little more suborally, and somewhat less near the horn. 

 There are exceedingly thin inner and outer laminae enclosing 

 a single layer of radially arranged secondary prisms. The 

 rather small surface meshwork of hexagons covers the bowl 

 everywhere, but the long aboral horn and the teeth are free 

 of prisms. The lumen enters the horn and elsewhere pre- 

 cisely conforms to the outer contour. 



Length, 334^1. 



The specimens of this expedition differ only in minor 

 ways from Hada's (i 93213) figured lorica. 



Parajiwclla promissa bears only slight resemblance to P. 

 subuhi. It is longer and much more slender, with a cylin- 

 drical instead of short, wide bowl, and the stronger, recurved 

 teeth are prominent. Its bowl and aboral horn are also un- 

 like those of P. elegans, and it could hardly be contused 

 with the other species, with which, also, it is seldom asso- 

 ciated in the Pacific. 



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

 (128) in the North Pacific middle latitudes, and one (130) 

 in the California region. 



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

 taken at 50 meters and 2 at 100 meters. Maximum fre- 

 quency, 45 per cent at station 130; another record above 

 minimum (9 per cent) from station 128; averages, 4 and 



26.5 per cent in pump and net samples, respectively. 

 Temperature: pump samples 8?96-i2'?9i (ii?25), net 

 samples 8?96-i2?9i (10^93). Salinity: pump samples 33.07- 

 3372 (33-39). net samples 33.40-33.72 (33.56). Density: 

 pump samples 25.13-26.14 (25.48), net samples 25.19-26.14 

 (25.66). pH: pump samples 8.06-8.26 (8.14), net samples 

 8.06-8.26 (8.16). 



Parafavella ventricosa (Jorgensen) Kofoid and Campbell 



PiirajavtUa ventricosa, Kofoid and Campbell, 1929, p. lyr, fig. 



314; Hada, 19326, p. 566, fig. 18. 

 Favella dctjtictdala var. robusta forma arctica Schulz and Wulff, 



1929, p. 345, fig. 2u: 



The rather large, stout, aborally inflated lorica, with a 

 short aboral horn, has a length of 5.17 oral diameters. The 

 thin oral margin has about 36 very short, subequidistant, 

 somewhat curved teeth. The bowl is cylindrical in the an- 

 terior 0.45 total length and then gradually expands in the 

 remaining section to 1.25 oral diameter at 0.65 total length 

 from the rim. Below this level it contracts rapidly as a 

 convex cone (60°) with a length of 0.26 total length. At its 

 lower end is the short (0.4 oral diameter), conical (5°), 

 pointed aboral horn. 



The thin wall (0.05 oral diameter) is subuniform, with 

 thin laminae and enclosed radial, rectangular prisms in a 

 single layer. The wall has distinct, rounded hexagons of 

 nearly uniform size at all levels; the aboral horn is hyaline 

 near the free tip. 



Length, 34611. 



Although in some ways differing from the typical form, 

 the lorica figured by Schulz and Wulff (1929) appears to 

 belong to this species. The loricae of this expedition con- 

 form neatly to type. 



Parafavella ventricosa differs from all the other species in 

 the extent of inflation of the aboral region, which has a 

 decidedly gourdlike shape. 



Recorded from one station (121) in the East Asiatic 

 marginal sea, in a net sample taken at 50 meters. Frequency, 

 minimum. 



Temperature, 3?77; salinity, 33.06; density, 26.28; pH, 

 7.92. 



XYSTONELLOPSIS J6rgensen 



XystoticUopsis, Kofoid and Campbell, 1929, pp. 238-239. 



Xystonellopsis has very much the same position and 

 abundance in the tropics as Parafavella in arctic seas. As 

 regards abundance, it is not so frequent, but is common in 

 small percentages in nearly any catch in warm seas. In 

 number of species it ranks somewhat better. The two genera 

 have in common the simple oral margin, the somewhat 

 similar form, and close likeness in wall structure. For these 

 reasons they are allied here. Kofoid and Campbell (1929) 

 placed Parafavella near Favella, partly for historical reasons, 

 and because the surface hexagonal patterning of the wall of 

 Favella, in some species, is much like that in Parafavella. 

 More careful work and consideration seem to indicate closer 

 relationship to the Xystonellidae on the part of Parafavella. 

 Both Xystonellopsis and Parafavella are specialized genera of 



