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



4. Spongolarcus amphicentria, Haeckel. 



? Amphicentria salpa, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 296 ; 



Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf. ii. fig. 18. 

 ? Spongurus salpa, Haeckel, 1862, Monogr. d. Kadiol., p. 466. 



Spongy network of the shell compact, its meshes about the same breadth as the bars. Surfair, 

 of the shell spiny, with some larger spines around the poles of the axis ; diameter of the internal 

 cavity about six times as large as the thickness of its wall. Proportion of the three dimensive 

 axes = 1:2:3. (Perhaps this Spongolarcus is identical with Amphicentria salpa, very imperfectly 

 described and figured by Ehrenberg, loc. cit.t) 



Dimensions. Length 014, breadth - 09, height 0'05 ; thickness of the spongy wall 0'015. 



Habitat. North Atlantic ; off Greenland, 1000 fathoms, Ehrenberg ; Station 64, depth (2700) 

 fathoms. 



Genus 271. Stypolarcus, 1 n. gen. 



Definition. L arcarida with lentelliptical spongy shell, composed of compact 

 spongy framework, without central cavity and medullary shell (without radial spines). 



The genus Stypolarcus differs from Spongolarcys in the absence of any central 

 cavity. This is quite filled up by spongy framework, which forms the whole mass 

 of the lentelliptical body. Stypolarcus bears therefore the same relation to Spongolarcus 

 that Styptosphcera does to Plegmosphcera. 



1. Stypolarcus spongiosus, n. sp. 



Lentelliptical shell composed in the whole mass of loose, spongy framework of similar texture, 

 with irregular meshes, about ten to twenty times as broad as the thin bars. Surface rough, without 

 radial spines. Proportion of the three axes = 3:4:5. 



Dimensions. Length - 2, breadth 016, height 012. 



Habitat. Antarctic Ocean, Station 157, depth 1950 fathoms. 



Family XXV. LARNACIDA, Haeckel, 1883 (PI. 50, figs. 3-8). 



Definition. L a r c o i d e a with a regular, completely latticed, lentelliptical cortical 

 shell, without open gates and annular constrictions; either this cortical shell or the 

 enclosed medullary shell is trizonal, composed of three elliptical, latticed, dimensive 

 girdles of different sizes, perpendicular one to another. 



1 Stypolarcus=Remp basket ; VTVKYI, Xajx&f. 



