126G THE VOYAGE OF H.M.S. CHALLENGER. 



which by communication of few larger and numerous smaller branches form an irregular network 

 with polygonal meshes. From each of the si.-i ribs arise two or three larger, perpendicular branches 

 of half the length, and from the network numerous smaller spines. All these dorsal spines of the 

 .shell are connected by a dense arachnoidal wicker-work. 



Dimensions. — Cephalis 0'02 diameter, thorax 0-0-4 long, O'S broad. 



Habitat. — Central Pacific, Station 271, surface. 



Subcrenus 2. Arachnocoronium, Haeckel. 



Definition. — Thorax with nine divergent ribs or radial beams, three of which are 

 primary or perradial, the other six secondary or interradial. (Sometimes eight or ten 

 occur instead of the nine normal ribs.) 



3. Arachnocorys cirmimtexta, Haeckel. 



Arachnocorys circumtexta, Haeckel, 1862, Monogr. d. Radiol., p. 304, Taf. vi. figs. 9-11. 

 Arachnocorys circumtexia, E. Hertwig, 1879, Organism, d. Radiol., p. 78, Taf. viii. fig. 2. 



Cephalis large, subspherical, with numerous roundish pores, and eight to ten slender, conical 

 horns twice the length. Thorax flatly conical, with nine strong, -straight, widely divergent, conical 

 feet, each of which bears in the middle of its outer side a perpendicular ascending branch of half the 

 length. These branches and the horns of the cephalis are connected by very thin, parallel, arach- 

 noidal threads. Network of the thorax irregular, with nine larger triangular holes at the base. 

 Collar septum with numerous, irregular, roundish pores. 



Dimensions. — Cephalis 0'04 to O'Oo diameter, thorax 0'08 to 012 long, 015 to 0'25 broad. 



Habitat. — -Mediterranean (Messina) ; Atlantic, Stations 347 to 354, surface. 



4. Arachnocorys enneaptera, n. sp. 



Cephalis large, campanulate, with irregular, polygonal pores, two larger stout pyramidal and 

 numerous slender, bristle- shaped horns. Thorax of the same structure as in the preceding species, 

 only the nine basal holes are of twice the size ; the lower network denser (as in Clathrocanium 

 diadcma, PI. 64, fig. 2). Collar septum with numerous, irregular, roundish pores. 



Dimensions. — Cephalis 0'05 diameter, thorax 012 long, 0^22 broad. 



Habitat. — Tropical Atlantic, Station 338, surface. 



5. Arachnocorys araneosa, n. sp. (PL 56, fig. 11). 



Cephalis large, subspherical, with circular, subregular, hexagonally framed pores, and twenty to 

 thirty slender, cylindrical, straight radial spines. Thorax flatly conical, nearly of the same shape as 

 in the two preceding species, but with nine longer ribs, and more irregular, broader network between 

 them, From the middle of each rib arises, nearly horizontally, a strong branch, which is directed 



