66 BULLETIN 104, UNITED STATES NATIONAL MUSEUM. 



Ammobacidites tenuimargo Cushmax, Bull. 71, U. S. Nat. Mus., pt. 1, 1910, 

 p. 117, figs. 180-183.— Pearcey, Trans. Roy. Soc. Edinburgh, vol. 49, 1914^ 

 p. 1010. 



Descnption. — Test elongate, compressed, early portion <lose 

 coiled, consisting of one to one and a half coils, later portion uncoiled, 

 consisting in fully developed spc( imens of 11 to 13 chambers in' reas- 

 ing gradually in size toward the apertural end, edges jagged, of 

 coarse sand grains; chambers irregular in size and shape, made of a 

 chitinous lining, to the outside of whidi are attadied sand grains; 

 wall thin on the inside, of chitin (?) and the exterior of angular 

 quartz grains; aperture a small, rounded, simple opening at the 

 end of the last-formed chamber; color white or gray. 



Length, up to 2.5 mm. 



Distribution. — ^This is a widely distributed species, the Atlantic 

 CltaUou/cr records being Faroe Channel, 530 fathoms (969 meters); 

 station 5, southwest of the Canaries, in 2,740 fathoius (5,011 meters); 

 323, east of Buenos Aires; 24, off Ciilebra Island, in 390 fathoms 

 (713 meters), and 78, off western Africa, in 1,000 fathoms (1,829 

 meters). 



Flint records the species from two Albatross stations, D2115, in 

 843 fathoms (1,542 meters), and D2584, in 541 fathoms (989 meters), 

 off the northeastern coast of the United States. Pcp.i'ccy records it 

 from two Scotia stations in the South Atlantic or Anttirctic in 1,775 

 and 2,620 fathoms (3,246 and 4,791 meters). 



I have had specimens from eight Aliatross stations, one in the Gulf 

 of Mexico, the others ofi the eastern and northeastern coast of the 

 United States. Depths range from 88 to 786 fathoms (161 to 1,437 

 meters), which is a nmch shallower range than fo)' A.foliacevs from 

 the same general region. 



Outside the Atlantic the only records seem to be those of the 

 CTiaUenger report, stations 218, north of New Guinea, 1,070 fathoms; 

 (3,109 meters); 168, east of New Zealand, 1,100 fathoms (2,012 

 meters), nnd 238, in the North Pacific, in 3,950 fatlioms (7,224 

 meters). 



An examination of spec imens mounted in Canada balsam shows 

 that there is a thin, brownish wall about each (hamber and that 

 they are very irregular, especially in the uncoiled part, the sand 

 grains, most of which are of clear quartz, being simply inc rusting 

 instead of forming a constituent part of the wall, as in most other 

 spec ies. There is some indie ation that there are both mic rospheric 

 and megalospheric forms in the material, the former with a coiled 

 portion with small proloculum, while the other has a larger first 

 chamber and the coil not so well developed. 



