TAXONOMY AND DISTRIBUTION 



21 



In form, these conform to the general shape of others; the 

 collar is sometimes more definitely separated from the bowl, 

 and the horn is lacking in a few. 



Cyttarocylis magna is most nearly like C. acutiformis, but 

 is larger, being up to 400U as against a maximum of 326^1; 

 its proportions are also different and there is less distinction 

 between collar and bowl. The ragged margin and aboral 

 horn are added differences. It differs in these characters 

 from C. cassis, and also in being longer and less stout, and 

 h.i\ ing a less flaring collar. It is unlike the other species and 

 can seldom be confused with them. 



Recorded from twelve stations, four in the Atlantic and 

 eight in the Pacific, as follows: one ( t6) in the Gulf Stream, 

 two ( 17, 18) in the Sargasso Sea, one (27) in the Atlantic 

 equatorial region, two (35, 35-36) in the Pacific equatorial 

 region, three (45, 70, 7s) in the Galapagos region, one (67) 

 in the South Pacific middle latitudes, and two ( 109, 151) in 

 the North Pacific trade region. 



There are 14 net samples, of which 1 was taken at the 

 surface, 5 at 50 meters, and 8 at 100 meters. Maximum fre- 

 quency, 32 per cent at station 35; other records above mini- 

 mum (2 to 25 per cent) from stations 35-36, 45, 67, 70, 7=5, 

 151; average in the Pacific, 9.2 per cent; in the Atlantic there 

 were only minimum occurrences. 



Temperature: Atlantic, i8?o8-23?64 (2i?2o); Pacific, 

 i4?33~2i?69 (17:24). Salinity: Atlantic, 36.03-36.82 (36.53 ): 

 Pacific, 34.42-35.47 (35.02). Density: Atlantic, 24.84-26.07 

 (26.00); Pacific. 24.48-26.28 (25.36). pH: Atlantic, 8.09- 

 S.27 (8.20); Pacific, 7.68-8.18 (7.98). 



Cyttarocylis mucronata Kofoid and Campbell 



(Figure 38) 



Cyttarocylis mucronata Kofoid and Campbell, 1929, p. 114, fig. 

 216. 



The elongated, acorn-shaped lorica, with contracted aboral 

 cone and aboral peg, has a length of 1.56 oral diameters. 

 The oral margin is coarsely irregular and rather ragged. 

 The short collar forms a segment of an inverted truncated 

 cone (50 ), and has evenly convex, full sides. Its length is 

 only 0.1 1 total length. The nuchal shelf is developed inside 

 at its lower edge. The shelf is thin, angled, upright, and not 

 well developed. The generally conical bowl is formed below 

 the clear-cut collar. The bowl is subdivided into a long sub- 

 oral inverted truncated conical section (20 ), with a length 

 of 1.0 oral diameter, and an aboral section which is a shorter, 

 wider inverted cone (62 ) with a length of 0.4 oral diam- 

 eter. The sides are barely convex. The aboral portion is a 

 pedicel-like inverted cone (58°) with a length of 0.2 oral 

 diameter and with convex sides. At its posterior end is a 

 tiny aboral peg. 



The wall has about 60 to 65 prevailingly hexagonal, rather 

 fine polygons around the throat, and 45 or more from oral to 

 aboral end. The polygons are larger and subuniform near 

 the rim, and become progressively smaller below. The wall 

 has a subuniform thickness of less than 0.02 oral diameter. 

 There is a single layer of secondary prisms. The aboral peg 

 is solid but otherwise the cavity follows the outer contour. 



Length, 152ft. 



The lorica figured (fig. 38) differs from that figured by 

 Kofoid and Campbell (1929) in having a coarsely ragged 

 oral rim and in being a little longer. 



Cyttarocylis mucronata differs from C. obtusa in its finer 

 surface reticulations and in the presence of an aboral peg. 

 This terminal point is distinct and invariable. The aboral 

 end of obtusa is blunt and squarely cut and lacks a peg. The 

 aboral cone of both species lacks a parallel in the genus. The 

 aboral truncation of C. mucronata is like that of C. conica, 

 but that species is longer and more slender as well as dif- 

 ferent in other ways. 



Recorded from four stations in the Atlantic, as follows: 

 two (19, 20) in the Sargasso Sea, and two (22, 25) in the 

 Atlantic equatorial region. 



There are 4 net samples, all taken at 100 meters. Maxi- 

 mum frequency, 3 per cent at station 19: other records at 

 the minimum; average, 1.6 per cent. 



Temperature, i4?6o-22?56 (i9?27); salinity, 35.70-37.05 

 (36.49); density, 25.38-26.67 (25.69); pH, 7.93-8.25 (8.12). 



Cyttarocylis obtusa Kofoid and Campbell 

 Cyttarocylis obtusa Kofoid and Campbell, 1929, p. 115, fig. 218. 



The elongate, rather slender, acorn-shaped lorica. with 

 contracted aboral cone and flattened end without peg, has a 

 length of 1.06 to 1.36 oral diameters. The oral margin is 

 minutely denticulate. The short collar forms a segment of 

 an inverted truncated cone (90 ), and has a length of 0.1 

 total length. Its sides are flat except just below the margin, 

 where they turn upward. The nuchal shelf is inconspicuous, 

 upright, and thin-edged. The bowl is quite convex conical 

 (30 ) in the suboral seven-tenths, and contracted (8o°) 

 below. Its sides are slightly sinuous. The aboral subdivision 

 is a flat-ended cone (36 ) and its aboral end has a diameter 

 of 0.14 oral diameter. Its sides are even. There is no trace 

 of an aboral peg. 



The wall has about 36 to 40 polygons around the neck 

 and 37 to 42 from oral edge to tip. The polygons are pre- 

 vailingly hexagonal, and larger in size in the suboral three- 

 tenths than below; in the posterior section they are only one- 

 third to one-half the size of those superior, and they tend to 

 be round. The wall is subuniformly 0.01 oral diameter in 

 thickness at the nuchal shelf, and there is but a single layer 

 of prisms. The cavity neatly conforms to the outer contour. 



Length, 135 to 157(1. 



Significant variations in length are probably correlated 

 with temperature adjustment. 



Cyttarocylis obtusa differs from C. mucronata in the dis- 

 tinct lack of an aboral peg, and in the generally smaller sur- 

 face polygons, more regular oral rim, and slimmer loricae. 

 The aboral end of C. conica is also truncated, but that species 

 has no aboral cone and the proportions are unlike, being 1.41 

 to 1.47 in conica. 



Recorded from three stations in the Atlantic, as follows: 

 two (18, 19) in the Sargasso Sea, and one (22) in the 

 Atlantic equatorial region. 



There are 3 net samples, of which 1 was taken at 50 



