TAXONOMY AND DISTRIBUTION 



49 



CRATERELLA Kofoid and Campbell 

 Craterella Kofoid and Campbell, 1929, p. 194- 



Craterella includes a few small tropical species as well as 

 one or two from cooler waters. Owing to the small dimen- 

 sions, the actual distribution is inadequately known, as are 

 the species. 



Two species are described here. 



Craterella armilla Kofoid and Campbell 

 (Figure 19) 

 Craterella armilla Kofoid and Campbell, 1929, p. 195, fig. 371. 



The tiny, saccular lorica, with low inner collar, repeated 

 outer collars, thimble-like bowl, and pointed aboral end, has 

 a length of 1.53 oral diameters. The oral margin is thin, 

 erect, and entire, and the inner collar spreads to the upper 

 end of the anteriormost of the two outer collars as a segment 

 of a cone (62 ) with a length of hardly 0.08 oral diameter. 

 The upper outer collar has a diameter of 1.15 oral diameters, 

 and flares (45°). It is separated by a trough from the inner 

 collar. The second outer collar has a diameter of 1.3 oral 

 diameters, and flares (90 ). It is separated from the first 

 outer collar by a trough. The pointed bowl has a length of 

 1.38 oral diameters. Its upper two-thirds is a truncated seg- 

 ment of an inverted cone (10°), and it has plane sides. The 

 aboral third of the bowl is conical (8o°), with convex sides 

 and a simple pointed aboral end. 



The wall is thick, with distinct laminae and interlaminar 

 prisms, and the surface shows rugosity. 



Length, 29U,. 



The lorica figured (fig. 19) has a pointed rather than 

 rounded aboral end. 



Craterella armilla differs from the other species in having 

 repeated collars and a rough surface. It is stouter than C. 

 protuberant and less contracted below. In general shape it 

 is like C. torulata, but the collar duplication differentiates it. 

 The collars flare instead of contracting as in C. urceolata. 

 Craterella aperta from Australia is not at all like armilla, or, 

 indeed, any of the others; it may not belong to Craterella. 



Recorded from two stations, one in the Atlantic and one 

 in the Pacific, as follows: one (23) in the Atlantic equatorial 

 region, and one (69) in the Galapagos region. 



There are 1 pump and 1 net sample, taken at the surface 

 and at 50 meters, respectively. Frequency, minimum. The 

 pump sample was taken in the Atlantic and the net sample 

 in the Pacific. 



Temperature: pump sample 21 ? 1 3, net sample 20?gg. 

 Salinity: pump sample 35.24, net sample 36.04. Density: 

 pump sample 24.66, net sample 25.30. pH: pump sample 

 8.12, net sample 8.14. 



Craterella urceolata (Ostenfeld) Kofoid and Campbell 



(Figure 20) 

 Craterella urceolata, Kofoid and Campbell. 1929. p. 196, fig. 368. 



The tiny lorica has a contracted aperture, flaring outer 

 collar, and wide, conical, pointed bowl, and its length is 1.24 



oral diameters. The oral margin is thin, sharp-edged, and 

 entire. The inner collar is a basal segment of a truncated 

 cone (8o°) with concave sides and a trough separating it 

 from the outer collar below. The outer collar has a diameter 

 of 1.2 oral diameters and a width of 0.16 oral diameter. It 

 flares (54°) from the bowl below, the upper diameter of 

 which is 1.1 1 oral diameters. The upper two-thirds of the 

 bowl is a segment of an inverted truncated cone (30 ), ami 

 the lower section is a wider cone (82 ). The sides of both 

 sections are convex, those of the upper section less so than 

 those of the lower. The aboral end is pointed but not pro- 

 longed or sharp. 



The wall is hyaline and thin, ami the cavity neatly follows 

 the outer contour. 



Length, 48^1. 



The lorica figured (fig. 20) has a more conical bowl, more 

 flare in the outer collar, and a narrower aperture than usual. 



Craterella urceolata differs from other species in having a 

 high inner collar, and in its stouter proportions. It is some- 

 what like C. obscura, but the bowl is not so long, and its 

 upper section is less cylindrical. It bears some likeness to 

 C. acuta, but that species has a higher, more flaring inner 

 collar, and a pointed, prolonged aboral end. Craterella pro- 

 tuberant has a blunt aboral horn. 



Recorded from one station (41) in the Galapagos region, 

 in a net sample taken at the surface. Frequency, minimum. 



Temperature, 20?42; salinity, 34.19; density, 24.06; pH, 

 8.11. 



ACANTHOSTOMELLA Jorgensen 



Acanthostomella, Kofoid and Campbell, 1929, p. 191. 



Acanthostomella adds a number of teeth to the outer collar 

 of Craterella. The genus is, however, remarkable in that 

 there are two sharp divisions in distribution. One group of 

 species is distinctly tropical, and the other group is of cold- 

 water facies. The latter mostly have distinct prismatic struc- 

 ture, whereas the former are glass-clear. The tropical species 

 usually have fewer and stronger teeth than the others. As 

 yet the genus is not so well known as it will be on further 

 examination of microplankton. 



Six species are described here. 



Acanthostomella elongata Kofoid and Campbell 

 Acanthostomella elongata Kofoid and Campbell, 1929, p. 192, 

 fig- 359- 



The tall lorica is shaped like a finger cot and has a sub- 

 hemispherical aboral end and a short spine; the length is 3.0 

 oral diameters. The oral margin is thin and entire, and the 

 inner collar is erect and rather wide. The outer collar has 

 24 outward-directed, low clawlike teeth, and hardly flares. 

 The upper bowl is cylindrical and about 2.6 oral diameters 

 in length. The lower bowl is about 0.4 oral diameter in 

 length, or less, and is an inverted convex cone (62 ). Its 

 lower end is drawn out into a tiny aboral spinule. 



The wall is thin: alveoles and laminae are present. 



Length, 7011. 



Acanthostomella elongata has a long cylindrical bowl, at 



