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DescriptionBenson, 1966, p. 266-268; pl. 18, figs. 7-8: Larcospira quadrangula Haeckel Larcospira quadrangula Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 696, Pl. 49, fig. 3. Fully developed tests subquadrangular in outline but with a sagittal constriction. Structure consisting of a double spiral representing a turning of two diagonally opposite wings of the second transverse girdle around the principal axis of the test; the other two wings of this girdle are absent. The wings are attached proximally to two oppositely placed, cylindrical, polar (coaxial with principal shell axis) beams, each of which arises from the innermost ellipsoidal shell from which is developed the inner trizonal shell surrounding it; the two spiral wings of the second transverse girdle arise from the trizonal shell. Each of the two wings are elongated parallel to the principal axis and form half-cylindroidal chambers whose openings face in opposite directions. Wings (chambers) supported by several thin, cylindrical, radial beams which arise from the surface of the inner trizonal shell. Lattice of test with subequal to unequal, subpolygonal pores, subregularly arranged, separated by thin intervening bars. Surface of test with scattered thorns or short, thin, conical spines. Measurements; based on 13 specimens from stations 27, 34, 60, 81, 91, 106, and 184: length of P1 axis (innermost shell) 31-36 µm, of P2 axis (inner trizonal shell) 68-82 µm, of P3 axis (sagittal constriction of fully developed forms) 135-209 µm, of T1 axis 18-27 µm, of T2 axis 43-64 µm, of T3 axis (maximum breadth of fully developed tests) 125-246 µm. Remarks. Haekel's illustration of this species does not show any differences from the Gulf specimens. However, he placed L. quadrangula in his subgenus Larcospirema Haeckel (1887, p. 696) which he defines as comprising tests with only one wing of the transverse girdle turning around the principal axis. His illustration, however, shows two wings turning around this axis. Distribution. This species is rare in the Gulf, occurring only at stations 27, 34, 46, 56, 60, 81, 91, 92, 93, 106, 115, and 184. Its near absence in the northern half of the Gulf indicates that it is an oceanic species. Haeckel reported this species from the central Pacific at Challenger station 265. It has not been reported from high latitudes; therefore, it is probably restricted to tropical regions.