N25

Carpocanistrum sp. A

Carpocanium sp. A, Nigrini, 1968, p. 55, pl. 1, fig. 4

DESCRIPTION

"Shell elongate, subcylindrical, smooth, with completely hidden spherical cephalis. Primary lateral and dorsal spines extend to the thoracic wall and draw it inwards, thus making the upper part of the shell trilobate.

"Thoracic pores subcircular to circular, approximately equal in size over most of the segment but smaller over the cephalic end, usually arranged in longitudinal rows, 9-13 in a vertical series, 7-10 on a half-equator. Mouth slightly constricted and sometimes surrounded by a well-developed, poreless, hyaline peristome. Terminal teeth, up to 14 on well-developed individuals, flat, usually truncate, parallel, as broad as, or broader than, the intervening spaces. Peristome may be smoothly terminated, or absent and termination ragged." (from Nigrini, 1968).

This species differs from other members of the genus by its elongate, subcylindrical thorax.

DIMENSIONS "Length of thorax 81-137mu; of peristome and terminal teeth up to 45mu (usually up to 18mu). Maximum breadth of thorax 63-81mu." (from Nigrini, 1968).

REMARKS

1. Benson's (1966) description and dimensions of this species (Carpocanium sp. in Benson, p. 438) are consistent with the above.

Plate 2l, figure 2

N26

RECENT DISTRI BUTION

1. Benson, 1966 (Carpocanium sp.); "confined to southern two-thirds of Gulf [of California ] . . . rare at all stations where it occurs, but it has a slightly greater frequency in the southern half of its range."

2. Nigrini, 1968, text-fig. 5; "Few in the region of the North Equatorial Current and in one equatorial sample near the coast of South America, most abundant in the northern part of the study area, rare or absent in all other samples examined . "