REPORT ON THE RADIOLARIA. 303 



Dimensions. — Longer axis of the shell 012, shortei* axis O'O!); pores and bars 0-004 to O'OOG ; 

 length of the polar spines — longer 0'12, shorter 0'06. 

 Habitat. — Fossil in Barbados. 



4. Lithomespilus jiammahundus, n. sp. (PI. 14, fig. 14). 



Proportion of the major axis to the minor = 4:3. Shell thin walled, with irregular, roundish 

 pores, partly simple, partly composed of three to six continent pores ; only six to eight pores on 

 tlie half eipiator, twice to four times as broad as the bars. Surface spiny. Length of the conical 

 irregular spines increasing towards the poles ; each polar spine surrounded by a flame-shaped, 

 circumpolar area of longer spines ; all large spines (also the j)olar spines) curved or contorted at 

 one pole and much stronger and more numerous than at the other ; length variable, often ecpial to 

 the longer axis. 



Dimensions. — Longer axis of the shell 0'12, shorter axis 0'09 ; pores 0'005 to 0'015, bars O'OOS to 

 0-005 ; length of the polar spines O'l to 0-1-5. 



Habitat. — Western part of the Tropical Atlantic, Station 347, depth 2250 fathoms. 



Genus 129. Lithapium,^ n. gen. 



Definition. — Ellipsida with simple ellij)soidal or ^jear-sliapecl shell; with a 

 single spine only situated at one pole of the main axis. 



The genus Lithapiuni represents a peculiar modification of Ellijysoxiphus ; one of 

 the two opposite polar spines disappears by reduction, and in this way only a single spine 

 remains, at one pole of the main axis. For this reason the shell assumes a characteristic 

 pear-shape, and may easily lie confounded with some similar Monocyrtida [Halicapsa). 



1. Lithapium pyriforme, n. sp. (PI. 14, fig. 9). 



Proportion of the longer axis to the shorter =6:5. Shell thin walled, with regular, circular 

 pores, four times as broad as the bars ; six to eight on the half equator. Surface a little thorny. 

 The single polar spines three-sided pyramidal, as broad at the base as one mesli, about as long as 

 the radius of the shell. (In the specimen figured, there was on the opposite pole a little rudiment 

 of the other lost polar spine ; it is missing in other specimens.) 



Dhnensions. — Major axis of the ellipsoidal shell 0-12, minor axis O'l ; pores 0'02, bars 0-005 ; 

 length of the single polar spine 0-05, basal thickness 0-02. 



Habitat. — Central area of the Pacific, Station 266, depth 2750 fathoms. 



2. Lithap)ium halicapsa, n. sp. (PI. 14, fig. 8). 



Proportion of the longer axis to the shorter = 6:5. Shell thin walled, with irregidar, lobed 

 meshes, six to eight on the half equator, twice to five times as broad as the bars ; each mesh 



' ii</ia!^iMm = Siliceous pear ; A/^of, x^aiov. 



