REPORT ON THE RADIOLARIA. 1213 



The genus Lamprodiscus, and the following nearly allied Lampromitra, differ from 

 all preceding Sethopilida in the complete connection of the three thoracic feet by lattice- 

 work, so that they are imbedded in the thorax -wall as prominent ribs and are not 

 prolonged beyond the margin as free feet. The shell is commonly very flat, conical or 

 pyramidal, sometimes nearly discoidal. The margin of Lamprodiscus is simple, smooth. 



1. Lamprodiscus monoceros, Ehrenberg. 



Lamprodiscus monoceros, Ehrenberg, 1872, Abhandl. d. k. Akad. d. "Wiss. Berlin, p. 295, Taf. vil 

 fig 2. 



Shell smooth, with deep collar stricture. Length of the two joints = 1:5, breadth = 1:8 

 Cephalis spherical, hyaline, without pores, with an oblique conical horn of the same length. 

 Thorax flat, campanulate, nearly hemispherical, with convex lateral outlines, and regular hexagonal 

 meshes, increasing gradually in size towards the mouth. Bars very thin. Peristome smooth. 



Dimensions. Cephalis 0'02 diameter; thorax 01 long, 016 broad. 



Habitat. Western Tropical Pacific (Philippine Sea), Station 200, surface. 



2. Lamprodiscus coscinodiscus, Ehrenberg. 



Lamprodiscus coscinodiscus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, 

 Taf. vii. fig. 3. 



Shell smooth, with sharp collar stricture. Thorax of the same form and structure as in the 

 preceding species, differing from it mainly in the structure of the smooth circular margin, which is 

 composed of a ring of very small square pores. Length of the two joints = 1:4, breadth = 1:8. 

 Cephalis with small hexagonal pores, without horn or with a short rudimentary horn. Lateral 

 outlines of the campanulate thorax in the upper part concave, in the lower convex. 



Dimensions. Cephalis 0'02 diameter ; thorax 0'08 long, 016 broad. 



Habitat. Tropical Pacific, Stations 206, 224, 266, &c., surface. 



3. Lamprodiscus tricostatus, n. sp. 



Shell smooth, with deep collar stricture. Length of the two joints =1:3, breadth = 1:7. 

 Cephalis spherical, with an oblique conical horn of twice the length and small circular pores. 

 Thorax flatly, conical, twice as broad as high, with straight lateral outline, and regular hexagonal 

 meshes, increasing gradually in size towards the mouth ; bars very thin. Peristome or margin of 

 the basal mouth circular, smooth. Very similar to Theopilium tricostatum (PL 70, fig. 6), but without 

 abdomen. Differs from the two preceding species mainly in the conical form of the thorax and 

 the less delicate network. 



Dimensions. Cephalis 0'03 diameter; thorax 01 long, 0'2 broad. 



Habitat. Cosmopolitan, Mediterranean, Atlantic, Indian Pacific ; surface. 



