1640 THE VOYAGE OF H.M.S. CHALLENGER. 



The central capsule of the Camiosphaerida is small (of O"! to O'lo in diameter) and 

 hidden in the aboral half of the enclosing inner shell, whilst the oral half of the latter is 

 filled up by the phseodium (figs. 2, 4). The structure of the capsule and of its three 

 openings seems to be the same as in the closely allied Aulosphaerida. I have, however, 

 not been able to recognise the two parapylse or secondary openings, and have only 

 observed the astropyle or the main-opening w^ith its radiate operculum surrounded by 

 the phaeodium, and directed with its tubular proboscis towards the mouth of the inner 

 shell. As R. Hertwig also could not recognise the two parapylse, it is not impossible 

 that they are wanting, and that the Cannosphserida possess only one opening, the 

 astropyle, like the Medusettida and Challengerida. The nucleus, enclosed in the central 

 capsule, is spherical, half or one-third as liroad as the latter, and contains numerous 

 nucleoli. 



Synopsis of the Genera of Cannosphmrida. 



Internal shell solid, without open pores, ...... 691. Cannosphcera. 



Internal sheU latticed, with open pore?, ...... 692. Caelacantha. 



Genus 691. Cannosphcera,^ Haeckel, 1879, Sitzungsb. med.-nat. 

 Gesellsch. Jena, Dec. 12, p. 6. 



Definition. — C a n n o s p h te r i d a with a solid, not latticed internal shell. 



The genus Cannosphcerct comprises those Cannospha^rida in which the inner shell is 

 formed by a thin solid siliceous-plate and exhibits no pores between the prominent bases 

 of the radial beams. 



1. Cannosp>hcera atlantica, n. .sp. (PI. 112, figs. 5, 6). 



Internal shell not niammillate, with fifteen to twenty radial I'ods, which are loosely studded 

 with single, scattered, simple, lateral spines. External shell with irregular, mostly hexagonal 

 meshes, armed with numerous scattered forks of paired divergent spines, and with twenty to 

 thirty larger simple radial spines, which are about half as long as the internal rods, and bear at the 

 distal end a verticil of three to live curved, simple, terminal branches. 



Dimensions. — Diameter of the inner shell O'l, of the outer 0'5. 



HaUtat. — Tropical Atlantic, Stations 347 to 349, depth 2250 to 2450 fathoms. 



2. Cannosphcera antarctica, u. sp. (PI. 112, figs. 1-3). 



Internal shell mammillate, with sixty to ninety radial rods, which are studded with cruciate 

 verticils of tridentate anchor-threads. External shell with irregular, mostly pentagonal meshes, 



' Ccm)iosp/i(Era = Sphere with tubules ; xxi^i/cc, ctpxl^a. 



