The genus Clathrolychnus may be derived directly from Clathrocorys, by development of an external arachnoidal mantle connecting the three wings and the three feet, and enveloping the whole shell, closing at the same time the basal mouth of the thorax by a fenestrated plate.
1. Clathrolychnus araneosus, n. sp. (Pl. [64], fig. 5).
Cephalis subspherical, with irregular, polygonal pores and a large pyramidal horn of twice the length. Length of the two joints = 4 : 9, breadth = 5 : 12. Thorax with three large triangular holes (twice as broad as the cephalis) between the three pyramidal, divergent feet, which at the distal end are connected by a narrow band of network, composed of two or three rows of polygonal pores. The entire pyramidal shell is enveloped by a very delicate web of irregular, polygonal meshes, closing also the basal mouth. (In fig. 5 the greater part of the web is taken off to demonstrate the large holes of the thorax). Only two feet are visible.
Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.09 long, 0.12 broad.
Habitat.—Central Pacific, Station 274, surface.
2. Clathrolychnus periplectus, n. sp. (Pl. [64], fig. 6).
Cephalis subspherical, with subregular, circular pores and a pyramidal horn of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3. Thorax with three large elliptical holes between the three pyramidal, divergent feet, which are connected at the distal end by a broad band of network, composed of five to ten rows of polygonal pores. The entire pyramidal shell is enveloped by a very delicate web, which on the sides is composed of subregular, square meshes, and on the closed mouth of polygonal meshes. (In fig. 6 only a part of the web is represented.)
Dimensions.—0.04 long, 0.05 broad; thorax 0.08 long, 0.14 broad.
Habitat..—Central Pacific, Station 271, surface.