REPORT ON THE RADIOLARIA. 1025 



Subfamily 1. TRIPOSPYRIDA, Haeckel, 1881, Prodromus, p. 441. 



Definition. Z ygospyrida tripoda, with three descending basal feet (the same as 

 in Cortina, an odd posterior or caudal foot and two paired anterior or pectoral feet). 



Genus 441. Tripospyris, 1 Haeckel, 1881, Prodromus, p. 441. 

 Definition. Z ygospyrida with three basal feet and one apical horn. 



The genus Tripospyris (PL 84, figs. 1-7) is in the large group of Spyroidea 

 probably the most original and typical form, from which, as a common ancestral form, 

 all other genera of this polymorphous suborder may be derived. The shell is usually 

 shaped like a nut or thorax, and exhibits two paired lateral chambers, which are separated 

 by a distinct sagittal ring and a slighter or deeper sagittal constriction. The dorsal rod 

 of the ring is prolonged at the upper pole into an ascending apical horn, at the lower 

 pole into a descending caudal foot, whilst two paired pectoral or lateral feet arise from 

 the anterior pole of the basal rod. These three divergent basal feet and the apical horn 

 are the same four typical radial spines which we have encountered already in Plagoniscus 

 (Plagonida), in Plectaniscus (Plectanida), in Cortina (Stephanida), and in Cortiniscus 

 (Semantida). Compare above, p. 891. From all these Plectellaria, Tripospyris 

 differs in the development of a complete bilocular lattice-shell, having the characters of 

 the true Spyroidea. The numerous species of this genus may be placed in different 

 subgenera, according to the different number of collar pores or cortinar pores in the 

 basal plate (two, three, four, six, or more). These differences are very important, 

 however difficult to make out ; the following system therefore is a provisional one, and 

 requires further accurate observations. 



Subgenus 1. Tripospyrantha, Haeckel. 



Definition. Basal plate with two large pores only (the primary jugular pores of 

 Semantis). 



1. Tripospyris cortina, n. sp. (PI. 95, fig. 1). 



Shell ovate, smooth, about as long as broad, with slight ovate sagittal stricture, and broad 

 primary ring in its wall. Basal plate with two large kidney-shaped collar pores only (cardinal 

 pores). Facial and occipital plates each with two pairs of large annular pores, and ten to twelve 

 pairs of small lateral pores. Apical horn and the three basal feet of equal length, one and a half 

 times as long as the shell, three-sided prismatic, straight, divergent. 



Dimensions. Shell 0'08 long, '0'09 broad ; horn and feet 0'15 long. 



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



1 Tripospyris = Basket with a tripod ; Tf/Vo?, airv^is- 



(ZOOL. CHALL. EXP. PART XL. 1886.) Rr 129 



