S85

Euchitonia furcata Ehrenberg

Euchitonia furcata Ehrenberg 1872a, p. 308; 1872b, pl. 289, pl. IV (iii), fig. 6; Ling and Anikouchine, 1967, p. 1484, pl. 189, 190, figs. 1-2, 5-7.

Euchitonia mulleri Haeckel, Nigrini, 1967, p. 37, pl. 4, figs. 1a, b

DESCRIPTION

"Shell bilaterally symmetrical with 3 arms of approximately equal length, elliptical in cross section. Arms arise from a central structure composed of 2 inner spherical shells and an outer oblate spheroidal shell, all quite smooth and connected by numerous, discontinuous, radial beams. In addition, there is an outer ring of mesh in the plane of the shell which is normally oriented perpendicular to the microscope axis. This central structure is the same as that of Amphirhopalum ypsilon.

"Arms fairly heavy, increasing in breadth distally and having a blunt or irregularly rounded termination; sometimes with 1-3 slender terminal spines. Proximally arms appear chambered, but a rather dense mesh of subcircular pores generally obscures distal chambers, and gives arms a spongy appearance. Paired arms form the smaller angle opposite odd arm and often curve slightly towards each other.

"A patagium may or may not be present. Specimens having a well-developed patagium are rare, and examination of it has not been sufficiently extensive to warrant any general conclusions. Usually, patagium shows partial development or, often, only a few initial branches are present. In other specimens there is no indication of a patagium forming." (from Nigrini, 1967).

DIMENSIONS "Average length of arms (measured from center of innermost sphere) 164-289 microns. Maximum breadth of arms 54-90 microns. Angle between paired arms 59 degrees - 94 degrees." (from Nigrini, 1967).

REMARKS

1. For a more complete synonymy and taxonomic discussion see Nigrini, 1967 and Ling and Anikouchine, 1967.

2. Benson's (1966) descriptions and dimensions of E. cf. furcata Ehrenberg (p. 228) and E. mulleri Haeckel (p. 232) are not consistent with the above.

Plate 11, figures 2a,b

S86

RECENT DISTRIBUTION

1. Nigrini, 1967, fig. 17; "Indian Ocean occurrences - Recognizable specimens of E. furcata are sparsely distributed in low latitudes, and are absent from samples taken south of 35 degrees S."

See also discussion of recent distribution for E. elegans herein.

2. Nigrini, 1968, text. fig. 14; cf. E. elegans herein;

3. Nigrini, 1970, fig. 17; belongs to a tropical assemblage derived by recurrent group analysis of North Pacific samples, but the species does range as far north as 40 degrees N in the western Pacific.

4. Molina-Cruz, 1975, Code S12; cf. E. elegans herein.

5. Robertson, 1975; cf. E. elegans herein.