608 THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions. Principal axis 0'05, transverse 0'04, sagittal axis 0'03 ; pores and bars O'OOG. 

 Habitat. Pacific, central area, Station 266, depth 2750 fathoms. 



Genus 267. Larcarium, 1 n. gen. 



Definition. L arcarida with a simple, lentelliptical latticed shell, without a 

 medullary shell ; surface covered with radial spines. 



The genus Larcarium differs from Cenolarcus only in the possession of radial 

 spines on the surface of the simple fenestrated lentelliptical shell. These spines are 

 commonly disposed symmetrically, opposite in pairs, either on the poles of the three 

 dimensive axes, or on the poles of certain diagonal axes. Larcarium differs from 

 the similar genera Larcidium, Larnacidium, and Lamacantha by the absence of any 

 medullary shell. 



1. Larcarium amphistyhim, n. sp. 



Shell thorny, with two large conical spines, opposite on botli poles of the principal axis, some- 

 what longer than it. Network of the shell regular, witli circular, hexagonally framed pores, twice 

 as broad as the bars ; about twelve pores on the half meridian, ten on the half equator. Proportion 

 of the three dimensive axes = 3:4:5. 



Dimensions. Principal axis (or length) 0'15, transverse axis (or breadth) O'0 12, sagittal axis (or 

 thickness) 0'09 ; pores O'Ol, bars O'OOS. 



Habitat. Pacific, central area, Station 274, depth 2750 fathoms. 



2. Larcarium staurostylum, n. sp. 



Shell smooth, with four short three-sided pyramidal spines of equal length, opposite in pairs on 

 the poles of the principal and lateral axes. Network of the shell regular, with circular pores of the 

 same breadth as the bars ; about eight pores on the half meridian, six on the half equator. Pro- 

 portion of the three dimensive axes = 2 : 2'5 : 3. 



Dimensions. Length of the shell 0'12, breadth O'l, thickness 0'08 ; pores and bars O'OOG. 



Habitat. South Pacific, Station 300, depth 1375 fathoms. 



3. Larcarium hexastylum, n. sp. 



Shell smooth, with six short conical spines of equal length ( = the shortest axis of the shell), 

 opposite in pairs on the poles of the three dimensive axes. Network of the shell subregular, with 



1 Larcarium = A kind of basket ; hxgxagioii. 



