60S THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions. — Principal axis 0'05, transverse O^O-i, sagittal axis 0i}3 ; pores and bars O'OOG. 

 HahitMt. — Pacific, central area, Station 266, depth 2750 fathoms. 



Genus 267. Larcarium,^ n. gen. 



Definition. — Larcarida 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 Larnacantlia by the absence of any 

 medullary shell. 



1. Larcarium amphistylum, n. sp. 



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

 what longer than it. Network of the shell regnlar, with circular, hexagonally framed pores, twice 

 as broad as the bars ; abont 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) 015, transverse axis (or breadth) 0"012, sagittal axis (or 

 thickness) 0-09 ; pores O'Ol, bars 0-005. 



Hahitat — Pacific, central area, Station 274, deptli 2750 fathoms. 



2. Larcarium staurostylum, n. sp. 



Shell smooth, with four short three-sided pyramidal spines of equal length, op)posite m pairs on 

 tlie 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 tlie half meridian, six on the half equator. Pro- 

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



Dimensions. — Length of the shell 042, breadth 04, thickness 0'08 ; pores and bars 0'006. 



Habitat— ^Vith Pacific, Station 300, depth 1375 fathoms. 



3. Larcarium hexasti/lum, u. 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 



' Larcarium = A kind of basket ; x«f xiij/o». 



