TAXONOMY AND DISTRIBUTION 



75 



tinnoina that confusion with other species is unlikely. The 

 dominant vertical ribs suggest relationship with Rhabdonella, 

 but horizontal crossbars are not developed in that genus, 

 although anastomoses of vertical ribs suggest a tendency 

 toward their definite differentiation. From any species of 

 Epiplocylis, E. nervosa differs in that the vertical ribs extend 

 the whole length of the bowl, and none of the members of 

 that genus have crossbars. 



Recorded from thirty stations, seven in the Atlantic and 

 twenty-three in the Pacific, as follows: five (17, 18, 19, 20, 

 21) in the Sargasso Sea, two (28, 29) in the Atlantic equa- 

 torial region, one (45) in the Galapagos region, four (52, 

 54, 63, 64) in the South Pacific middle latitudes, two (83, 

 84) in the region of South Pacific island fields, eight (133, 

 134, 135, 136, 137, 146, 147, 148) in the California region, 

 four (138, 139, 140, 150) in the North Pacific trade region, 

 and four (141, 142, 144, 145) in the North Pacific middle 

 latitudes. 



There are 29 pump and 12 net samples, of which 3 were 

 taken at the surface, 14 at 50 meters, 23 at 100 meters, and 

 I at 150 meters. Maximum frequency, 8 per cent at stations 

 136, 144; other records above minimum (2 to 6 per cent) 

 from stations 18, 19, 20, 21, 54, 64, 133, 135, 141, 142, 145, 

 147, 148; averages, 2.6 and 2.1 loricae in Atlantic and Pacific 

 pump samples, and 1.7 and 2.6 per cent in Atlantic and 

 Pacific net samples, respectively. 



Temperature: Atlantic, pump samples 20^32-27? 11 (22?78), 

 net samples 2o?32-26?79 (23? 15); Pacific, i4?73-27?46 

 (i8?94) and i8?74-20?07 (i9?3i), respectively. Salinity: 

 Atlantic, pump samples 36.22-36.81 (36.59), net samples 

 36.31-37.15 (36.73); Pacific, 34.27-36.49 (34.96) and 34.32- 

 35.40 (34.90), respectively. Density: Atlantic, pump samples 

 23.62-26.07 (25.18), net samples 23.79-26.07 (25.20); Pacific, 

 22.90-25.48 (24.53) snd 24.24-25.37 (24.88), respectively. 

 pH: Atlantic, pump samples 8.20-8.29 (8.23), net samples 

 8.19-8.27 (8.24); Pacific, 8.07-8.39 (8.26) and 8.16-8.39 

 (8.27), respectively. 



XYSTONELLIDAE Kofoid and Campbell 



Xystonellidae Kofoid and Campbell, 1929, p. 225. 



Included in this family are four genera: Parafavella, 

 Xystonellopsis, Pariindella, and Xystonella. All four are 

 present in the material of this expedition. The family is 

 widely spread in most seas except the Antarctic. 



PARAFAVELLA Kofoid and Campbell 



Parafat'ella Kofoid and Campbell, 1929, pp. 157-158. 



Parajai'ella is one of the most interesting genera of the 

 Tintinnoina in extent of speciation and extraordinary num- 

 bers of individuals; the latter fact offers extensive oppor- 

 tunity for statistical investigation on a quantitative basis, 

 which should at some time be undertaken in special memoirs. 

 The geographical distribution of the genus is no less inter- 

 esting. Limited to regions of low temperature and never ex- 



tending far below about latitude 45° north, Parajavella offers 

 opportunity for study of the effects of latitude and tempera- 

 ture on evolution. Certain species are limited to the Pacific, 

 and others to the North Atlantic. Only battered specimens 

 extend the range south of the arctic regions, where the genus 

 reaches its greatest development in numbers and kinds; 

 perhaps polar seas will reveal yet more when these are more 

 closely examined. 



Eleven species are described here, of which one is new, and 

 another is designated by a new name. 



Parafavella affinis, new species 

 (Plate I, figure 5) 



The lorica is bell-shaped, rather stout, and 2.05 oral diam- 

 eters in length. The oral margin carries a crown of about 

 26 sharp, spikelike teeth; these spread outward at about 60° 

 from the horizontal, and are evenly spaced, narrow, antl 

 rounded in section. The conical bowl (30°) may be sub- 

 divided into two regions. The anterior section has a length 

 of I.I oral diameters; it is an inverted truncated cone (12°), 

 and the diameter at the aboral, truncated end is 0.74 oral 

 diameter; the sides are full, distinct arcs. The aboral sub- 

 division has as its base the lower end of the section above it; 

 it is conical (45°), with full sides, and is 0.85 oral diameter 

 in length. The aboral end is the simple, sharp end of this 

 cone, and lacks special differentiation. 



The wall is evenly and smoothly contoured, with not the 

 slightest trace of irregularity. It is uniformly less than 0.03 

 oral diameter in thickness. It has, in section, typical second- 

 ary prisms in a single layer enclosed by laminae. The 

 surface has subuniform hexagons at all levels, except near 

 the aboral tip and in the teeth. The cavity follows the con- 

 tour exactly. 



Length, 1 071.1; oral diameter, 521^1. 



Parafavella affinis resembles P. pacifica closely in general 

 form, but has a less elongated upper bowl and fewer teeth 

 (26 as against 32 to 42). It bears some likeness to P. acumi- 

 nata, but its margins bear teeth, and there is a less sharp 

 distinction between upper and lower bowls. Parafavella 

 acuminata is figured by Kofoid and Campbell (1929) as 

 P. greenlandica. 



Recorded from ten adjacent stations in the Pacific, as fol- 

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

 six (118, 119, 120, 121, 122, 123) in the East Asiatic mar- 

 ginal sea, and two (124, 125) in the Alaskan secondary 

 region. 



There are 25 pump and 14 net samples, of which 13 were 

 taken at the surface, 14 at 50 meters, and 12 at 100 meters. 

 Parafavella affinis occurs equally at all levels examined. 

 Frequency, 80 per cent at station 124, at the surface; 500 

 loricae counted in the pump sample at station 119, at 50 

 meters; all records, except that at station 118, above mini- 

 mum (2 to 28 per cent); average in net samples, 22.7 per 

 cent; in pump samples, 52 loricae (i to 500). 



Temperature: pump samples 2?oi-i2"56 (6?2i), net 

 samples 2?oi-8?22 (5? 10). Salinity: pump samples 32.63- 



