REPORT ON THE RADIOLARIA. 1191 



nodal points large blunt conical papillae. Basal plate without larger pores. Horn three-sided 

 pyramidal, one-third as long as the shell, gradually passing into the slender neck of the bottle. 



Dimensions. Shell 0'22 long, 015 broad; horn 0'07 long. 



Habitat. Central Pacific, Station 265, depth 2900 fathoms. 



5. Halicapsa pyriformis, Haeckel. 



1 Haliomma pyriforme, Bailey, 1856, Amer. Journ. Sci. and Arts, voL xxii. p. 1, pi. i. fig. 29. 



Shell pear-shaped, a little longer than broad, covered with numerous short conical spines 

 Pores subregular, circular, of nearly equal size, twice as broad as the bars. Basal plate with four 

 crossed larger ovate pores (two larger cardinal and two smaller jugular pores). Horn stout 

 pyramidal, scarcely one-fourth as long as the shell. 



Dimensions. Shell 016 long, 014 broad ; horn 0'04 long. 



Habitat. Fossil in Barbados, living in the North Pacific (Kamtschatka) ? 



6. Halicapsa hystrix, n. sp. (PI. 53, figs. 5, 6). 



Shell pear-shaped, subspherical, a little longer than broad, with scattered stout pyramidal spines 

 about as long as the radius of the shell. Pores subregular, circular, three times as broad as the 

 bars. Basal plate (fig. 6) without larger pores. Horn very large, pyramidal, longer than the shell. 



Dimensions. Shell 01 long, 0'09 broad; horn 013 long. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



Genus 533. Archicapsa, 1 Haeckel, 1881, Prodromus, p. 428. 

 Definition. A rchicapsida without apical horn. 



The genus Archicapsa differs from the preceding Halicapsa in the absence of the 

 apical horn, and represents the simplest form among the Monocyrtida clausa, a simple, 

 ovate, or pear-shaped shell without any appendages. The characteristic structure of 

 the basal lattice-plate (with three or four large cortinar pores) makes it probable that 

 Archicapsa has been derived either from Halicapsa, by loss of the horn, or directly 

 from Dictyospyriy, by reduction of the sagittal ring and constriction. 



1. Archicapsa triforis, n. sp. (PI. 53, figs. 1, 2). 



Shell pear-shaped, smooth, one and a half times as long as broad. Pores subregular, circular, 

 of about the same breadth as the bars. Basal plate (fig. 2) with three very large pores, three times 

 as broad as the others (one odd sternal pore and two paired cardinal pores). 



Dimensions. Shell 0'09 long, OD6 broad. 



Habitat. Central Pacific, Station 271, depth 2425 fathoms. 



1 Archicapsa = Primordial capsule ; ei^ix.^a. 



