EEPORT ON THE RADIOLAEIA. 1145 



Genus 503. Tridictyojnis,'^ Haeckel, 1881, Prodromus, p. 428. 



Definition. — A r c h i p i 1 i d a (vel Monocyrtida trii-adiata aperta) with three latticed 

 terminal feet. Shell ovate or subconical, with an apical horn. 



The genus Tridictyojyus diflfers from the nearly allied Trijnlidium in the possession 

 of three large fenestrated shovel-shaped feet, forming direct prolongations of the large 

 conical shell. The lattice work exhibits a peculiar elegant structure recurring in the 

 similar, perhaps nearly related, Cephalospyris (PI. 83, fig. 10; PI. 96, fig. 28). The 

 central capsule is large, ellipsoidal or ovate, and fills up the greater part of the shell 

 cavity (compare R. Hertwig, 1879, loc. cit., p. 75). 



1. Tridictyopus vatillum, n. sp. (PL 51, fig. 8). 



Shell campamilate, about as long as broad (excluding horn and feet). Pores irregular, 

 polygonal, in the middle part more regular, triangular. Horn short and stout, three-sided 

 pyramidal. Three feet large, triangular, shovel-shaped, about half as long as the shell. 



DimensioTis. — Shell 0'14 long, 0"15 broad. 



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



2. Tridictyojyus conidus, n. sp. (PI. 51, fig. 7). 



Shell campanulate conical, about one and a half times as long as broad (excluding horn and 

 feet). Pores mostly triangular, disposed in subregular hexagonal figures, which are separated by 

 bands of smaller irregular polygonal pores. Horn short and stout, three-sided pyramidal. Three 

 feet triangular shovel-shapeil, convergent, about one-sixth as long as the shell. 



Dimensions. — SheU O'o long, 0'2 broad ; horn 0'04 long, feet 005 long. 



Habitat. — Equatorial Atlantic, Station 347, depth 2250 fathoms. 



3. Tridictyopus elegans, R. Hertwig. 



Trii:Udijo2ms elegans, E. Hertwig, 1879, Organismus d. Radiol., p. 75, Taf. vii. fig. 3, 3a, 3&. 



SheU slender, conical, campanulate, about twice as long as bioad (excluding horn and feet). 

 Most pores subregular triangular, with some irregular polygonal ones intermingled. The horn in the 

 two observed specimens was broken off, together with the conical apex of the shell. Three feet 

 triangular shovel-shaped, about one-sixth as long as the shell 



Dinuiisions. — SheU 0'3 long, 0'15 broad ; feet 0'05 long. 



Habitat. — Mediterranean (Messina), E. Hertwig, surface. 



' Tridictyopus — Shell with three lattice-feet ; Tg/«, o/kti/o;/, xoii;. 



(ZOOL. CHAI.L, EXP. PART XL. — 188G.) El' 144 



