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



1. Xiphoptera tessaractena, n. sp. 



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Four equatorial spines in the outer third crossed by two opposite transverse apophyses, each of 

 which bears on its distal side two to three branches, perpendicular to the apophysis and parallel 

 to the spine itself. Sixteen other spines much smaller, in the outer third crossed by two simple 

 opposite transverse apophyses. 



Dimensions. Length of the four major spines 018, of the sixteen minor O05 to 01. 



Habitat. North Pacific, Station 238, surface. 



2. Xiphoptera dodecactena, n. sp. (PI. 131, fig. 3). 



Four equatorial spines one and a half times to twice as long and broad as the eight tropical 

 spines. These twelve spines have the same form and are crossed in their distal third by two large 

 opposite transverse apophyses, each of which bears on its distal side two to four branches, perpendi- 

 cular to the apophysis and parallel to the spine. Eight polar spines much smaller than the twelve 

 others, simple, without apophyses. The central capsule of this species exhibited a conical 

 protuberance around the base of each individual spine. 



Dimensions. Length of the twelve larger spines 01 to 0'2, of the eight smaller 0'02 to O'OG. 



Habitat. Central Pacific, Station 272, surface. 



3. Xiphoptera icosactena, n. sp. 



Four equatorial spines about twice as long and four times as broad as the sixteen other spines. 

 All twenty spines crossed in the outer third by two large opposite transverse apophyses, each of 

 which bears on its distal side two to four branches perpendicular to the apophysis and parallel to 

 the spine itself. 



Dimensions. Length of the four equatorial spines 0'26, of the sixteen smaller Oil to 014. 



Habitat. South Pacific, Station 288, surface. 



Genus 340. Lithoptera, 1 J. Miiller, 1858, Mouatsber. d. k. preuss. Akad. 



d. Wiss. Berlin, p. 155. 



Definition. Quadrilonchida with two opposite branched and latticed 

 apophyses, either on each radial spine or only on a part of the twenty spines. 



The genus Lithoptera, founded by Johannes Miiller in 1858 for the first observed 

 Mediterranean species, Lithoptera fenestrata, differs from all other Quadrilonchida in 

 the fenestrated form of the apophyses, which he compared to the sails of a wind- 

 mill. This peculiar fenestration is effected by two to four parallel pairs of opposite 

 apophyses, which are crossed by perpendicular branches, parallel to the spine itself. 



1 Lithoptera = Stone viru;; x/0os, im^n. 



