390 THE VOYAGE OF H.M.S. CHALLENGEE, 



5. Panarium tuhidarium, n. sp. (PI. 40, fig. 9). 



Surface of the cortical shell thorny, covered with small spines. Both proximal chambers nearly 

 kidney-shaped, with irregular, polygonal pores, three to four times as broad as the bars ; five to six 

 pores on the half meridian, nine to ten on the half equator of each chamber. Both distal chambers 

 nearly hemispherical, with a circle of ten to twelve large square pores at their base ; the other pores 

 much smaller, irregular, roundish. Polar tubuli prismatic, with prominent edges, nearly half as 

 long as the main axis, only one-fourth as broad as the equatorial constriction. Pores of the tubuli 

 very small, in longitudinal series between the edges. 



Dimensions.- — Total length of the shell (without tubuli) fl4S to 0"2, greatest breadth (in the 

 equator of the proximal chambers) 0-07 to O'OD ; pores 0-003 to O'Ol, bars 0-002 to 0-004 ; length 

 of the polar tubuli 0-06 to 0-09, breadth of them O'OIS to 0-02. 



Habitat. — Pacific, central area. Stations 270 to 272, depth 2425 to 2925 fathoms. 



Genus 168. Peripanarium,^ n. gen. 



Definition. — P an art id a -with double cortical shell and double medullary shell, 

 with t-tt'o hollow fenestrated tubes, opposite on the jioles of the main axis. 



The genus Peripanarium differs from Panarium only in the development of an 

 outer reticulated envelop, which mantle-like surrounds the shell and represents a second 

 or external cortical shell. It bears therefore to Panarium the same relation as 

 Peripanartus to Panartvs, &c. 



1. Peripanarium cenoconicum, n. sp. 



Internal cortical shell with four kidney-shaped chambers of nearly tlie same form and size ; 

 theii" pores irregular, roundish, twice to four times as broad as the bars. External cortical shell 

 cylindrical, hemispherical at both poles, with irregular, very small, roundish pores, only one-third to 

 one-half as large as those of the internal. From both poles of the internal cortical shell arises a 

 hollow conical fenestrated tube, which perforates the external. The outer free part of this slender cone 

 equals in length the inner part or the distance between the two cortical shells, which is about equal 

 to the length of one chamber. External surface covered with small thorns. (This species has the 

 same appearance as Desmartus larvalis, PI. 40, fig. 12, hut has only four chambers instead 

 of six.) 



Dimensions. — Main axis (without cones) 0"23, greatest breadth Oil ; pores of the inner cortical 

 shell 0-004 to 0-009, of the outer 0-002 to 0-003 ; bars of the foi-mer 0-002, of the latter 0-001 ; 

 total length of the polar cones 0-05, basal thickness of them 0-03. 



Habitat. — West Tropical Pacific, Station 225, depth 4475 fathoms. 



' Peripanarium = Paiutrium (or bread-basket) with luantle. 



