EEPORT ON THE RADIOLARIA. 1357 



Genus 597. Tlieopera} Haeckel, 1881, Prodromus, p. 436. 



Definition. — Tlieoperida (vel Tricyrtida trii-adiata clausa) with three lateral 

 wings, beginning from the sides of the thorax and prolonged into the sides of the 

 abdomen. 



The genus TJieopera differs from the two preceding genera in the greater extension 

 of the three lateral wings, which are prolonged from their original base, the thorax, into 

 the inversely conical abdomen. It has therefore an intermediate position between the 

 preceding and the following genera. It differs from the similar Pterocanium and 

 Tlieopodium in the closure of the constricted and fenestrated mouth. 



1. Tlieopera prismatica, n. sp. (PI. 67, fig. 7). 



Rhopalocanium prismalicuvi, Haeckel, 1879, Atlas, pi. Ixvii. fig. 7. 



Shell three-sided prismatic, with three broad and long hyaline wings, which are prolonged from 

 the coUar stricture almost to the basal end, with three parallel edges. Length of the three joints 

 = 2 : 8 : 10, breadth = 3 : 9 : 8. Cephalis hemispherical, with a conical horn of the same length. 

 Thorax subspherical ; abdomen inversely ovate ; pores of both small, regular, circular, of equal size. 



Dimensions. — Length of the three joints, a 0-02, b O'OS, c O'l ; breadth, a 0-03, h 0-09, c 0-08. 



Eabitat. — South Atlantic, Station 332, depth 2200 fathoms. 



2. Tlieopera pyramis, Haeckel. 



Rhopalocanium sp., Bury, 1862, Polycystins of Barbados, pi. xviL fig. 8. 



Shell three-sided pyramidal, with three broad and long hyaline wings, which are prolonged from 

 the collar stricture almost to the basal end, with three diverging edges. Length of the three joints 

 = 3:8:11, breadth = 4 : 8 : 9. Cephahs subspherical, with a conical horn of the same length. 

 Thorax hemispherical ; abdomen inversely campanulate. Pores in the abdomen twice to three 

 times as broad as in the thorax, subregular, circular. Differs from the preceding species mainly in 

 the broader pyramidal form and the divergence of the wings. 



Dimensions. — Length of the three joints, a 0-03, h 0-08, c Oil ; breadth, a 0-04, I O'OS, c 0-09. 



Habitat. — Fossil in Barbados. 



3. TTieopeni fusiformis (PI. 67, fig. 5). 



Shell nearly spindle-shaped, rough, with two shght strictures. Length of the three joints = 

 2:3:6, breadth = 2 : .5 : 4. Cephalis hemispherical, large, with an obhque conical horn of the same 

 length. Thorax hemispherical ; abdomen inversely conical. Pores irregular, roundish, of very 



' Theopera = Divine pouch ; 6i6:, viioci. 



