1696 THE VOYAGE OF H.M.S. CHALLENGER. 



covered with three or four verticils of four Jong curved bristles; at the distal apex inflated, with 

 four crossed, divergent, stout, curved horns. Around the pyramidal base of each spine a corona of 

 eight pores (two on each of the four faces). Mouth cruciform, with four triangular, convergent teeth. 



Dime-nsions. — Diameter of the shell 0"16, length of the spines 0'18. 



Habitat. — South Pacific, Station 298, depth 2225 fathoms. 



Genus 712. Circo.'ipathis,^ Haeckel, 1879, Sitzungsb. med.-nat, Gesellsch. 



Jena, Dec. 12, p. 5. 



Definition. — Circoporida with a subregular, spherical, or polyhedral shell, 

 composed of fourteen triangular, nearly equal plates, with, nine corners, from which 

 arise nine radial spines, symmetrically disposed. 



The genus CiixosjKithis exhibits the remarkable and peculiar form of a "Tetra- 

 decahedron," or a subregular polyhedron with fourteen triangular faces, thirty edges, and 

 nine corners, from which arise nine radial sj^ines. These lie in three meridional planes, 

 which are crossed at equal angles (three ecpiidistant spines in each plane). The same 

 interesting form occurs also in some Astrosphserida, which bear nine regularly disposed 

 radial spines, as Haliomma echinaster. All four observed species of Circospathis are 

 South Atlantic. 



1. Circosjmthis furcata, n. sp. (PI. 115, figs. 4-6). 



Shell polyhedral or nearly spherical, with nine prominent corners, from which arise nine radial 

 spines, about as long as the diameter of the shell. The polygonal plates of the shell are separated 

 by high crests, usually hexagonal or pentagonal, irregular, about twelve to fifteen on the half 

 meridian. Eadial spines cylindrical, straight, about as long as the diameter of the shell, with 

 spirally turned edges, covered with numerous curved bristles, at the distal end forked ; the two 

 fork branches curved, one-third as long as the simple basal part. The inflated base of each spine is 

 surrounded by a corona of nine to twelve ovate basal pores. Mouth pentagonal, with five tliick, 

 mammillate and spinulate, somewhat convergent teeth (fig. 5). 



Dimensions. — Diameter of the shell 0'6, length of the spines 0'5. 



Habitat. — South Atlantic (east of Buenos Ayres), Station 325, depth 2650 fathoms. 



2. Circospathis novena, n. sp. (PI. 117, figs. 3, 3a). 



Shell polyhedral (tetradecahedral), with fourteen triangular, plane, or slightly convex faces, covered 



with small, irregular, polygonal (usually hexagonal) plates, and nine prominent corners, from which 



arise nine radial spines, shorter than the diameter of the shell. Each spine is surrounded at the 



broader base by a circle of twelve to sixteen pores and a corona of bristles, and bears at the 



■ Circospathis = Shell with verticils around tlie epines ; kI^ko;, vicuii;. 



