REPORT ON THE RADIOLARIA. 1569 



4. Cannopilus hemisphcericus (Haeckel). 



Dictyocha hemisphcerica, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 266. 



Each pileated piece of the skeleton is nearly hemispherical, with thirteen meshes ; six lower 

 and larger meshes in the sides of the truncated six-sided pyramid, seven others in the convex surface 

 of the upper ring (one central with six surrounding it). From the six corners of the lower ring 

 arise six horizontal perradial spines. From the inside of the same ring (probably on the side of 

 the six ascending interradial beams) spring six centripetal teeth. 



Dimensions. Diameter of the basal ring 0'02, of the apical ring O'Ol. 



Habitat. North Atlantic ; Bermuda (Bailey). 



5. Cannopilus cyrtoides, n. sp. (PI. 114, figs. 11, 12). 



Dictyocha cyrtoides, Haeckel, 1881, Prodromus. 



Each pileated piece of the skeleton is an eight-sided truncated pyramid, or nearly hemispherical. 

 From the basal ring arise twenty-four thorns or teeth, eight longer perradial centrifugal teeth 

 placed almost horizontally, and between these sixteen shorter adradial teeth, directed downwards 

 and somewhat centripetally. The network of the small hat is composed of seventeen meshes, 

 arranged in two rows. The eight lower meshes are hexagonal, separated by six interradial ascend- 

 ing beams, and twice as large as the eight upper pentagonal meshes, which are separated by eight 

 perradial beams, and enclose an apical central mesh. 



Dimensions. Diameter of the basal ring O04, of the apical ring 0'005. 



Habitat. Central area of the Pacific, Station 266, depth 2750 fathoms. 



Family LXXIII. AUL AC A NTH ID A, Haeckel (Pis. 102-105). 

 Aulacanthida, Haeckel, 1862, Monogr. d. Radiol., p. 262. 



Definition. PH^EODARIA with an incomplete skeleton, composed of numerous hollow 

 radial tubes, which pierce the spherical calymma and touch with their proximal ends the 

 surface of the tripylean central capsule. 



The family Aulacanthida represents a large and interesting group of PILEODAKIA, 

 differing from all other families of this legion in the possession of numerous large radial 

 tubes, which pierce the gelatinous and alveolated calymma in a radial direction, and come 

 in contact with the outer surface of the central capsule by their inner or proximal ends, 

 whilst their outer or distal ends project over the surface of the spherical calymma, 

 and develop a great variety of manifold branches and terminal appendages. Usually 

 (with the exception of a single genus only) the surface of the calymma is covered by an 



(ZOOL. CHALL. EXP. PART XL. 1886.) Rr 197 



