REPORT ON THE RADIOLARIA. 1575 



The genus Aulacantha, hitherto the only representative of this family, was founded 

 by me in 1860 for the cosmopolitan Aulacantha scolymantha, the most common 

 and most widely distributed of all the members of the family. It is the simplest 

 form of the Aulographida, or of those Aulacanthida in which the spherical surface of the 

 calymma is densely covered with interwoven tangential needles. The large radial tubes 

 of Aulacantha possess a very simple shape, as in the preceding Aulactinium, and have 

 neither lateral nor terminal branches. 



1. Aulacantha scolymantha, Haeckel. 



Aulacantha scolymantha, Haeckel, 1862, Monogr. d. Radiul., p. 263, Taf. ii. figs. 1, 2, Taf. iv. 



figs. 1-5. 

 Aulacantha scolymantha, R. Hertwig, 1879, Organism, d. Radiol., p. 88, Taf. ix. fig. 3, Taf. 



x. figs. 7-10. 



Radial tubes cylindrical, straight, of nearly equal breadth throughout their whole length, some- 

 what inflated on the proximal basal end, smooth throughout the greater part of their length, but 

 in the distal third dentate, with numerous (ten to forty) small pointed teeth, which are curved 

 outwards, and shorter than the thickness of the tube. 



Dimensions. Length of the tubes 0'5 to 2'0, breadth O'Ol to 0'02. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific ; at many Stations ; surface 

 and at various depths ; the most common of all Aulacanthida. 



2. Aulacantha tubulosa, n. sp. 



Eadial tubes cylindrical or nearly spindle-shaped, straight, gradually tapering towards the two 

 pointed ends, twice as broad in the middle third as in the outer and inner third, smooth in the 

 inner half, dentate in the outer half, with very numerous (one hundred to two hundred) short conical 

 teeth, which are scarcely one-fourth as large as the greatest breadth of the tube. 



Dimensions. Length of the tubes 0'4 to 0'5, breadth in the middle part 0'02 to 0'03. 



Habitat. Central Pacific, Stations 271 to 274, surface. 



3. Aulacantha spinosa, n. sp. (PI. 105, fig. 4). 



Eadial tubes cylindrical, straight, of equal breadth throughout their whole length, rounded on 

 the proximal base, smooth in the inner proximal half, dentate or spinescent in the outer distal half, 

 with numerous (fifty to eighty) slender conical teeth, which are curved forwards, increasing in size 

 towards the distal end, and somewhat longer than the breadth of the tube. 



Dimensions. Length of the tubes 0'8 to T2, breadth 0'015 to 0'02. 



Habitat. North Pacific, Stations 241 to 253, surface. 



