4 6 



OCEANIC TINTINNOINA OF LAST CRUISE OF CARNEGIE 



the Pacific, as follows: one (9) in the Atlantic drift, and one 

 (116) in the North Pacific middle latitudes. 



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

 surface and 2 at 50 meters. Maximum frequency, 8 per cent 

 at station 116; frequency at station 9, 2 per cent; averages, 

 1.5 and 5.5 per cent in the Atlantic and Pacific, respectively. 



Temperature: Atlantic, 8?o6-i 1 : 12 ( 909); Pacific, 1 1 ? 1 8— 

 i6?07 (i3?62). Salinity: Atlantic, 35.11-35.14 (35.12); 

 Pacific, 33.79-34.02 (33.90). Density: Atlantic, 26.88-27.37 

 (27.12); Pacific, 24.99-25.83 (25.41). pH: Atlantic, 7.96- 

 8.u8 (8.02); Pacific, 8.11-8.17 (8.14). 



PTYCHOCYLIDAE Kofoid and Campbell emended 

 Ptychocylidae, Kofoid and Campbell (part), 1929, p. 172. 

 Only the single genus Ptychocylis occurs in the family. 



PTYCHOCYLIS Brandt emended Jorgensen 

 Ptychocylis, Kofoid and Campbell, 1929, pp. 185-186. 



Ptychocylis is related in form and in wall structure to 

 Favella, Protocymatocylis, and Cymatocylis, and more re- 

 motely to Poroecus. Ptychocylis is the northern representa- 

 tive of these mostly southern and tropical genera. 



Ptychocylis is distinctly a northern genus. Rarely does it 

 extend as far south as latitude 40 north. Mostly it occurs 

 in the Barents Sea, Davis Strait, Sea of Okhotsk, Bering 

 Sea, and north of the West Wind Current, often in minus 

 temperatures. Only washed and battered empty loricae enter 

 San Francisco Bay. 



Six species are described here. 



Ptychocylis acuta Brandt emended Kofoid and Campbell 

 Ptychocylis acuta, Kofoid and Campbell, 1929, p. 187, fig. 353. 



The generally cylindrical lorica, with acutely conical aboral 

 end, has a length of 1.72 oral diameters. The oral margin is 

 fairly regularly serrate, with about 70 triangular, erect teeth 

 set upon a narrow, hyaline cuff with a width of only 0.03 

 oral diameter. The bowl swells concavely below the cuff to 

 a diameter of 1.17 oral diameters at 0.13 oral diameter below 

 the rim. This projecting ledge then rapidly narrows again 

 and there is a cylinder below it. A second ledge, with a 

 diameter of 1.17 oral diameters, is located at 0.45 oral diam- 

 eter below the rim. The lower part of the bowl is a segment 

 of an inverted truncated cone (25°) with a length of 0.77 

 oral diameter at its lower end, which is 1.22 oral diameters 

 below the rim; the diameter at this level is 0.83 oral diam- 

 eter. The aboral region forms a hollow-sided segment of an 

 inverted truncated cone (8o°) with a length of 0.25 oral 

 diameter. Its lower end is 1.47 oral diameters below the rim. 

 The diameter at this level reaches 0.38 oral diameter. The 

 distally blunted aboral horn is an inverted cone (50 ) with 

 a length of nearly 0.27 oral diameter. 



The wall has a uniformly thin inner and outer lamina, 

 and clear interlaminar substance fills the space between. The 

 outer surface is irregularly reticulated with a scarcely raised 

 network of secondary structure. 



Length, 120 to 145(1. 



Ptychocylis acuta resembles P. wailesi in having an acute 

 aboral end, but the lower bowl is fuller and relatively shorter. 

 Ptychocylis glacialis has a sharply pointed aboral end, and 

 the remaining species are so different that they can hardly 

 be confused with acuta. 



Recorded from one station (119) in the East Asiatic mar- 

 ginal sea, in a pump sample taken at the surface. There 

 were 2 loricae. 



Temperature, 6:91; salinity, 32.96; density, 25.85; pH, 

 7.96. 



Ptychocylis arctica Brandt emended Kofoid and Campbell 

 Ptychocylis arctica, Kofoid and Campbell, 1920, p. 187, fig. 351. 



The large, stout, bullet-shaped lorica, with blunted, flat- 

 tened aboral end, has a length of 1.48 oral diameters. The 

 oral margin has about 50 large, triangular, erect teeth, evenly 

 spaced and subequal. These denticles arise from a hyaline 

 cuff with a width of only 0.03 oral diameter. Below the cuff 

 the bowl extends as a narrow cylinder for a width of 0.05 

 oral diameter, and an angular ledge with a width of 0.06 

 oral diameter and a diameter of 1.12 oral diameters occurs 

 below this cylinder. The bowl extends as a cylinder below 

 the ledge once more, and is 0.25 oral diameter in width. At 

 its lower end is a second ledge with a width somewhat less 

 than that of the upper one, but with the same diameter. The 

 lower part of the bowl contracts as an inverted truncated 

 segment of a cone (22°) with a width of 0.78 oral diameter; 

 its sides are plane to slightly full. The aboral region is an 

 inverted convex cone (83 ) with a width of 0.26 oral diam- 

 eter. The aboral end is squarely truncated, and its diameter 

 is 0.19 oral diameter. 



The wall is thickened in the ledges to 0.05 oral diameter, 

 and is less than half as thick in the lateral region. Laminae 

 are difficult to detect, and the wall is homogeneous. The 

 outer surface is reticulated with rather small prisms, the 

 edges of which are weakly raised, giving the surface, espe- 

 cially at the aboral end, a pitted structure. The clear cuff 

 rests upon the dense bowl. The lumen does not enter the 

 ledges. 



Length, 120 to 140(1. 



Ptychocylis arctica differs from P. drygalsk^u in the longer, 

 lower bowl and general bullet shape. From P. basicurvata 

 it differs in aboral truncation rather than simple aboral 

 rounding. The remaining species have altogether different 

 aboral ends. 



Recorded from one station (10) in the Atlantic drift, in 2 

 net samples, 1 taken at the surface and 1 at 50 meters. Fre- 

 quency, minimum. 



Temperature, 9?86-io?94 (io?4o); salinity, 34. 94-34- <is 

 (34.945); density, 26.77-27.96 (27.36); pH, 8.04-8.08 (8.06). 



Ptychocylis drygalskii Brandt 



Ptychocylis drygalskii, Kofoid and Campbell, 1929, p. 188, fig. 

 350; Hada, 1932^, p. 567, fig. 11. 



The heavy-set lorica, with little-developed ledges and 

 truncate conical, flattened aboral end, has a length of 1.4 

 oral diameters. The oral margin is regularly provided with 



