REPORT ON THE RADIOLARIA". 1267 



outwards. These branches are connected with the spines of the cephalis as well as with the distal 

 half of the ribs, by dense and delicate arachnoidal network, composed of parallel, very thin, siliceous 

 threads (in fig. 11 only partially represented). Collar septum with numerous irregular, roundish 

 pores. 



DimcTusions. — Cephalis 0-04 diameter, thorax O'l long, 0-2 broad. 



Habitat. — Central Pacific, Station 270 to 274, surface. 



6. Arachnocorys arachnodiscus, n. sp, 



Cephalis small, campanulate, conical, with a single very large conical central horn, and numerous 

 smaller accessory spines. Thorax in form and structure similar to that of the three preceding 

 species, but much flatter, being nearly discoidal. The meshes of the network are smaller and more 

 numerous, irregularly polygonal, and the nine basal holes little larger. Collar septum with four large 

 meshes (as in PI. 60, fig. 6). 



Dime'asions. — Cephalis 0'25 long, 0'3 broad ; thorax 0'04 long, 0'24 broad. 



Habitat. — North Pacific, Station 248, surface. 



7. Arachnocorys trifida, n. sp. 



Cephalis large, campanulate, with irregular, roundish pores and numerous ramified spines ; in the 

 centre of the top a larger pyramidal oblique horn of twice the length. Thorax cap-shaped, flatly 

 vaulted, with nine strong convex ribs, prolonged into slender free feet. Three of these nine riljs are 

 the centrifugal prolongations of the three cortinar bars (united in the centre of the collar stricture, 

 separating its three large cortinar meshes); the other six are diverging lateral branches of the former, 

 arising in pairs at both sides of its base. All nine ribs are connected by delicate arachnoidal net- 

 work with irregular polygonal meshes. From its surface arise thin bristles, and from the base of each 

 main rib a stout, perpendicular branch. All these dorsal spines are connected l)y irregular, 

 arachnoidal wicker-work, covering thorax and cephalis. (A remarkable primitive species ?) 



Dimensions. — Cephalis 0'05 long, 0'06 broad ; thorax 0'07 long, 018 broad. 



Habitat. — Central Pacific, Station 27l, depth 242.5 fathoms. 



Subgenus 3. Arachnocorythium, Haeckel. 



Definition. — Thorax with a variable number of radial ribs (twelve to twenty or 

 more), prolonged into free terminal feet. 



8. Arachnocorys polyjJtera, n. sp. 



Cephalis large, subspherical, with iiTegular, roundish pores and numerous radial spines. Thorax 

 flatly conical, with numerous radial ribs (twenty to thirty), which are in the distal half free, in the 

 proximal half connected by delicate arachnoidal wicker-work, with ]Dolygonal, irregular meshes. 

 From its dorsal face arise numerous radial spines, whic'h are connected together, and with the 

 cephalic spines, by very thin and numerous threads, parallel between every two spines. Similar to 



