Shell campanulate, tuberculate, with deep sagittal stricture and irregular polygonal pores; two pairs of larger pores at the flattened occipital face (fig. 20). Basal plate with four large collar pores. Apical horn very long, thirty to forty times as long as the shell, slender three-sided prismatic, straight, at the distal end irregularly branched, besom-shaped. Four basal feet half as {1045}thick as the horn, eight to twelve times as long as the shell, bristle-shaped, irregularly curved and branched, divergent, at the distal end besom-shaped. Central capsule very large; the enclosed small campanulate part sends out through the four collar pores four very long club-shaped basal lobes, half as long as the feet; each lobe contains a large oil-globule (fig. 19). _Dimensions._--Shell 0.036 diameter; horn 1 to 1.5 mm. long, feet 0.3 to 0.4 long. _Habitat._--Central Pacific, Station 270, surface. 4. _Tetraspyris calcarata_, n. sp. Shell campanulate, smooth, very similar to that of the preceding species, but differing in the following characters:--the two inferior occipital pores are four times (in the preceding twice) as large as the two superior; the apical horn bears at its distal end only three simple branches; the sternal foot is smaller than the three others, arises higher, is more divergent and curved, and bears at its base a large horizontal conical spur. _Dimensions._--Shell 0.035 diameter; horn 1 to 1.2 long, feet 0.2 to 0.3 long. _Habitat._--Central Pacific, Station 266, surface. 5. _Tetraspyris scoparia_, n. sp. Shell campanulate, rough, very similar to the two preceding species, but differing in the following characters:--the four occipital pores are of nearly equal size; the apical horn is simple, not branched; the four feet are forked near the base, so that apparently eight feet diverge, each in the distal half richly branched, besom-shaped. _Dimensions._--Shell 0.038 diameter; horn 1 to 1.1 long, feet 0.4 to 0.5 long. _Habitat._--Central Pacific, Station 268, surface. Genus 452. _Tessarospyris_,[70] Haeckel, 1881, Prodromus, p. 442. _Definition._--#Zygospyrida# with four basal feet crossed in pairs (two sagittal and two lateral). Apex without horn. The genus _Tessarospyris_ differs from the preceding _Tetraspyris_, its ancestral genus, in the absence of the apical horn, and therefore bears to it the same relation that _Tristylospyris_ does to _Tripospyris_. 1. _Tessarospyris clathrobursa_, n. sp. (Pl. 53, fig. 8). _Clathrobursa dictyopus_, Haeckel, 1881, Prodromus, p. 439, and Atlas, pl. liii. fig. 8.