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



arms. (Very similar to the ellipsoid Spongurus cylindricus, Monogr. d. Radiol., p. 465, Taf. xxvii. 

 fig. 1, but differs in the compressed lenticular (not ellipsoidal) form of the central disk; the 

 transverse section of the arm is elliptical, not circular.) 



Dimensions. Eadius of the arms 01, breadth - 04. 



Habitat. Pacific, central area, Station 270, depth 2925 fathoms. 



3. Spongolena cypselura, n. sp. 



Arms nearly triangular, not longer than broad, about half as large as the elliptical central disk, 

 at the broader distal end with two very large, widely divergent lateral spines, and between them 

 several smaller, like the tail of a swallow. Surface thorny. 



Dimensions. Radius of the arms 0'2, distal breadth (without spines) 015, basal breadth 0'07. 



Habitat. Pacific, central area, Station 272, depth 2600 fathoms. 



Genus 261. Spongobrachium? Haeckel, 1881, Prodromus, p. 461. 



Definition. S pongodiscida with two opposite spongy arms on the margin of 

 the disk, connected by a spongy patagiurn of different texture. 



The genus Spongobrachium differs from the foregoing only in the loose spongy 

 patagium, which envelops both opposite spongy arms. It corresponds to Amphymenium 

 among the Porodiscida and to Amphiactura among the Coccodiscida. 



1. Spongobrachium ellipticum, Haeckel. 



Spongocydia elliptica, Haeckel, 1862, Monogr. d. Kadiol., p. 470, Taf. xxviii. fig. 2. 

 Spongodiscus ellipticus>, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 844. 



Arms nearly square, scarcely as long and broad as the radius of the circular central disk, at 

 the broader distal end truncated. Patagium complete, enveloping the whole disk with the arms, 

 and forming a larger elliptical disk of looser framework. (In my Monograph, 1862, loc. cit., I 

 had not distinguished the opposite darker arms, opposite in the longer axis of the elliptical disk, 

 from the enveloping looser framework of the patagium. In larger specimens of the Challenger 

 collection this distinction is very evident.) 



Dimensions Piadius of the arms 012, breadth 0'05 ; major axis of the elliptical patagium 0'24, 

 minor 016. 



Habitat Cosmopolitan ; Mediterranean, Atlantic, Pacific, surface. 



2. Spongobrachium lanceolatum, n. sp. 



Arms club-shaped, twice as long as broad, at the distal end pointed, five times as long as the 



radius of the circular central disk. Patagium complete, enveloping the whole disk with the arms, 



1 Spongobrachium = Spongy shell with two arms ; 



