EEPORT ON THE EADIOLARFA. 621 



3. Larnacalpis macrococcus, n. sp. 



Cortical shell with spiny surface and regular network; pores circular, small, of the same 

 breadth as the bars; about twenty-two on tlie half meridian, nineteen on the half equator. Pro- 

 portion of the three axes = 2:3:4. Medullary shell two-thirds as large as the cortical, with four 

 wide internal semicircular gates. 



Dimensions. — Length of the cortical shell 01, breadth 0'075, height O'Oo; pores and bars 0'00.''>; 

 length of the meduUary shell 0-06G, breadth 0-05, height 0-0:32. 



Hahitat. — Western Tropical Pacific, Station 224, depth 1850 fathoms. 



4. Larnacalpis siibsplicerlca, n. .s[). 



Cortical shell with rough surface and irregular networ]>; ; roundish pores twice to iive times as 

 broad as the bars; about twenty-four on the half meridian, twenty-one on the half erpiator. Pro- 

 portion of the tliree axes = l'2 : 1%3 : r4. MeduUary shell half as large as the cortical, with four 

 elliptical internal gates. 



Dimensions. — Length of the cortical shell 014, breadth 013, height 012; pores 0'004 to O'Ol, 

 bars 0-002 ; length of the medullary shell 0-08, breadth 0-07, height 0-00. 



Habitat. — I'acific, central area, Station 266, depth 2750 fathoms. 



5. Larnacalpis triaxonia, n. sji. (PI. 50, fig. 3). 



Cortical shell with smooth surface and peculiar network, composed of four meridian rows of 

 larger pores (five large elliptical pores on each half meridian, the largest in the equator) and 

 numerous small irregular pores between them. Proportion of the three axes = 2 : 3 : 4. Medullary 

 sheU with four semicircular internal gates, about one-fourth as large as the cortical, connected witli 

 it Viy six thin radial beams, opposite in pairs in the three dimensive axes. 



Dimensions. — Length of the cortical shell 0-14, breadth O'l, height 0-07; large pores 0-03, 

 small pores 0-002 to 0-01, bars 0-002 to 0-01; length of the medullary shell 0-04, breadth 0-03, 

 height 0-02. 



Habitat. — Pacific, central area. Station 263, depth 2650 fathoms. 



Genus 275. Larnacantha,^ n. geu. 



Definition. — Lam acid a with a simple lentelliptical cortical shell, armed with 

 symmetrically disposed radial spines. Medullary shell double, Zar/ioci//«-shaped. 



The genus Larnacantha has the same characteristic shell-formation as tlie foregoing 

 Larnacalpis, and differs from it only in the possession of radial spines, which are 

 symmetrically distributed on the surface in a definite order. Commonly these spmes 

 are external prolongations of the internal radial beams, which connect the double 

 Xarnocz7/a -shaped medullary shell with the simple lentelliptical cortical shell. 



1 Laraocanf7Mi = Chest with spines ; 7i«(»«J, oinanCa. 



