TAXONOMY AND DISTRIBUTION 



51 



(41, 69) in the Galapagos region, and one (65) in the South 

 Pacific middle latitudes. 



There are 4 net samples, of which 2 were taken at the 

 surface and 2 at 100 meters. Frequency, 2 per cent at 

 station 69. 



Temperature: Atlantic,20?32;Pacific,i5?oo-2i?i3(i8?86). 

 Salinity: Atlantic. 36.81; Pacific, 34.19-35.24 (34.57). Den- 

 sity: Atlantic, 26.01; Pacific, 24.06-25.44 (24.72). pH: At- 

 lantic, 8.21; Pacific, 8. 10-8. 12 (8. 11). 



Acanthostomella norvegica (Daday) Jorgensen 



(Figures 21, 22, 23) 



Acanthostomella norvegica, Kofoid and Campbell, 1929, p. 193, 

 fig- 363; Bernstein, 1931, p. 14; Hada, 19321;, pp. 56-57, fig. 

 22; 1932&, p. 567, fig. 20. 



The short, stout, cuplike lorica, with short, incurved, claw- 

 like teeth, wide, swollen bowl, and aboral end with tiny 

 nipple, has a length of 1.14 to 1.71 oral diameters. The oral 

 margin is thin. The inner collar is less than o.i oral diameter 

 in width, and has a spreading base. There is a trough be- 

 tween it and the outer collar. The outer collar flares (40° to 

 50°) and has outwardly convex sides. On its free edge are 

 20 to 36 incurved, clawlike, sharply pointed, narrow tri- 

 angular, subequal, and subequidistant teeth. The upper 

 section of the short, wide bowl is an inverted basal segment 

 of a full truncated cone (4°) with a length of 0.73 to i.o 

 oral diameter. The lower section is at first 42° to 63°, and 

 later 90° to 145°, thus forming a rounded cone, or subhemi- 

 sphere, with pronouncedly convex sides. The aboral end has 

 a nipple-like horn with a length of not more than o.i oral 

 diameter. 



The wall is uniformly thin (hardly 0.02 oral diameter). 

 There are laminae with rectangular, subequal prisms in a 

 single layer. The inner collar is glass-clear. The horn is 

 solid. The aboral half of the bowl is mostly plastered with 

 adherent fecal matter. 



There are 2 oval macronuclei. 



Length, 45 to 501.1. 



Three extreme variants are shown (figs. 21-23). Of these, 

 one (fig. 23) is hollow-sided in the upper bowl, and swollen 

 at about i oral diameter below- the rim. Its bowl is longer 

 than usual. The others figured are more nearly of the usual 

 type. Hada (1932a, 1932^) figures 2 loricae, one with a 

 longer horn than the other. The horns on these specimens 

 are longer and more sharply pointed than those on the 

 Carnegie specimens. The bowls are not so long as that of 

 the extreme specimen of this collection, nor so short as those 

 of others. In other characters, however, all these agree. 



Acanthostomella norvegica is, perhaps, closest to A. 

 gracilis, which has the same general habitat. It is aborally 

 expanded, however, and has a nipple. Its lower bowl is 

 conical rather than cylindrical, and the aboral region is less 

 angular. Its bowl is not so long as that of A. elongata, and 

 it is altogether unlike the tropical species of the genus in 

 most characters. 



Recorded from fifteen stations, eight in the Atlantic and 

 seven in the Pacific, as follows: one (7) in the North Sea, 



three (8, 10, 11) in the Atlantic drift, two (12, 13) in the 

 American cold-water region, one (14) in the Gulf Stream, 

 two (117, 126) in the North Pacific middle latitudes, four 

 (120, 121, 122, 123) in the East Asiatic marginal sea, one 

 (124) in the Alaskan secondary region, and one (130) in 

 the California region. Acanthostomella norvegica has a pro- 

 nounced northern and temperate distribution and appears 

 elsewhere either accidentally in water of warmer origin, as 

 in the Gulf Stream (station 14), or as a subsurface dweller. 



There are 14 pump and 16 net samples, of which 9 were 

 taken at the surface, 13 at 50 meters, and 8 at 100 meters. 

 Maximum frequency, 68 per cent at station 13; other records 

 above minimum (2 to 56 per cent) from stations 7, 11, 14, 

 117, 120, 121, 123, the greatest frequencies being in surface 

 catches; averages, 19.0 and 1.8 loricae in Adantic and Pacific 

 pump samples, and 14.8 and 7.5 per cent in Atlantic and 

 Pacific net samples, respectively. 



Temperature: Atlantic, net samples 4?i8-i4?02 (8^55), 

 pump samples 7?oi-i4?95 (ii?07); Pacific, ■i°.i-j-i7,°gi 

 (9?io) and 2?05-i2?56 (7?i8), respectively. One record 

 of 14? 02 was in the Gulf Stream, where 3 empty loricae 

 were recorded in 2 samples. Salinity: Atlantic, net samples 

 32.68-35.95 (34.73). pump samples 32.68-35.10 (34.25); 

 Pacific, 33.06-34.22 (33.60) and 32.66-34.22 (33.07), respec- 

 tively. Density: Atlantic, net samples 24.94-27.96 (27.04), 

 pump samples 24.94-27.42 (26.14); Pacific, 25.19-26.41 

 (26.00) and 25.26-26.48 (25.84), respectively. pH: Adantic, 

 net samples 7.93-8.08 (8.01), pump samples 7.92-8.18 (8.05); 

 Pacific, 7.72-8.26 (7.99) and 7.84-8.06 (7.98), respectively. 



Acanthostomella obtusa Kofoid and Campbell 



Acanthostomella obtusa Kofoid and Campbell, 1929, p. 194, 

 fig. 361. 



The short, stout, cuplike lorica, with tall, thickened inner 

 collar, heavy outer collar, few teeth, and short, blunt aboral 

 horn, has a length of i.6 to 1.7 oral diameters. The oral 

 margin is thin, erect, and entire, and the wider outer collar 

 has 20 short, stout, outward-projecting, triangular teeth. 

 The outer collar is less than i.i oral diameters in diameter 

 and barely flares. The upper bowl is a full truncated cone 

 (20°), and the lower three-tenths widens out as a hollow 

 cone (68°). The lower part of the aboral three-tenths widens 

 yet more. The aboral horn is about rectangular in section, 

 being 0.25 oral diameter in length. Its free tip is squarely 

 truncated. 



The thin, hyaline wall of the bowl is slightly thickened in 

 the collar. 



Length, 26 to 36|i. 



Acanthostomella obtusa differs from the other species in 

 having a stout, squarish aboral horn. The remaining species 

 have either no developed horn, or else a sharply pointed one. 

 Acanthostomella conicoides has fewer teeth (6 to 8) and is 

 more slender. Acanthostomella gracilis is alveolar, and has 

 a relatively longer, more cylindrical bowl, and no horn. 



Recorded from two stations (45, 80) in the Galapagos 

 region, in a net and a pump sample taken at the surface and 

 at 50 meters, respectively. Frequency, 2 per cent at station 80. 



