REPORT ON THE RADIOLARIA. 843 



14. Lychnaspis cataplasta, n. sp. 



Parmal pores very small, circular, half as broad as the bars, and much smaller than the irregular 

 sutural pores. By-spines zigzag, as long as the diameter of the shell. Eadial main-spines very 

 thin and long, needle-shaped, cylindrical, five to six times as long as the diameter of the shell. 

 Sutures perfectly obliterated. (This stunted sjDccies is one of the smallest of the Dorataspida.) 



Dimensions. — Diameter of the shell 0'05, parmal pores 0"0015, sutural pores O'Ol, bars 0'n02. 



Habitat. — Antarctic Ocean (off Kerguelen Island), Station 149, surface. 



Genus .3G4. Icosaspis,^ Haeckel, 1881, Prorlromus, p. 468. 



Definition. — D o r a t a s p i d a with twenty plates, which are perforated by one 

 hundred and sixty to three hundred or more parmal pores (in each plate four crossed 

 aspinal pores, and around them four to twelve or more coronal pores). Surface wdthout 

 by-spines. 



The genus Icosaspis and the closely allied Hylaspis differ from all other Tessara- 

 spida in the increased number of the parmal pores. Whilst this number in all other 

 genera is eighty (only four crossed pores in each plate), here it amounts to one hundred 

 and sixty to three hundred or more (sometimes more than a thousand) ; in each shield 

 four primary, crossed " aspinal pores " being surrounded by a circle of four to twelve 

 or more " coronal pores." The number of sutural pores in these two genera is also 

 increased. 



Subgenus 1. Icosasparium, Haeckel. 



Definition. — Condyles of the neighbouring plates connected by pemianent open 

 sutures ; therefore the whole shell composed of twenty separated pieces of acanthin. 



1. Icosasjiis tabulata, n. sp. (PI. 136, fig. 2). 



Parmal meshes all of nearly equal size and form, square, four times as broad as the bars, 

 little larger than the triangular or polygonal sutural meshes. In each plate fifty to seventy 

 (regularly sixty-four) quadrangular pores, viz., four primary square aspinal meshes, forming 

 together a regular square surrounded by two to three coronas of rectangular (not quite regular) 

 coronal meshes (six to eight in each transverse row). Eadial spines tetrapterous, prismatic, 

 with four thin and broad wings, from wliich arise the crossed bars between the four primary 

 pores. Outer part of the spines longer than the inner. Commonly the condyles of the plates 

 are only contiguous ; sometimes they grow together, and this form approaches Icosaspis tetragonopa. 



Dimensions. — Diameter of the shell 0-25 to 0-3, of the pores 0'02, bars 0'005. 



Habitat. — -North Pacific, Station 244, depth 2900 fathoms. 



' Icosaspis = SheU yith twenty shields ; itx.oai, xct^Is- 



