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



Biviensions. — Length of the cortical shell 0'24, breadth 0'18 ; thickness of its wall 0'035 ; 

 diameter of the medullary shell 0'06. 



Habitat. — North Pacific, Station 244, depth 2900 fathoms. 



5. Spongodruppa ellijitica, Haeckel. 



Acanthosphcera elliptica, Ehreaberg, 1872, Abhandl. J. k. Akad. d. Wiss. Berlin, p. 285, Taf. 

 vii. fig. 4. 



Cortical shell nearly twice as long as broad, four times as broad as the ellipsoidal meduDary 

 shell. Spongy framework compact, with small ineshe.s. Surface covered with very numerous 

 short radial spines, about as long as the meduUary shell. 



Dimensions. — Length of the cortical shell 0-2, breadth Oil ; length of the medullary shell 

 0-04, breadth O'OS. 



Habitat. — PhUippine Sea, Ehrenberg, Station 206, depth 2100 fathoms. 



6. Spongodrujjpa polyacantJia, Haeckel. 



Haliomma jjohjacanfhum, 3. Midler, 1858, Abhandl., p. 36, Taf. i. figs. 10, 11. 

 Haliomma pohjacanthum, Haeckel, 1862, Monogr. d. Radiol., p. 430. 



Cortical shell one and a third times as long as broad, twice as broad as the ellipsoidal 

 medullary shell. Spongy framework loose on the surface, with large regular meshes. Surface 

 covered with fifteen to twenty thick, conical spines, about as long as the radius of the sheU. 



Dimensions. — Length of the cortical shell 0'12, of the medullary shell 0'09 ; cHameter of the 

 medullary shell 0-05 to 0-06. 



Habitat. — Mediterranean (south coast of France) ; Atlantic (Canary Islands), Station 354, surface. 



Genus 149. Spongatr actus, ^ n. gen. 



Definition. — S p o n g u r i d a with spongy ellip.soidal cortical .shell, enclosing a 

 simple, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur 

 two ojDposite strong spines. 



The genus Spongutractus difi'ers from Spongodrvjrpa hy development of two strong 

 spines in the axis of the shell, on its two opposite poles ; therefore it bears the same 

 relation to the latter that Lithatractus does to Druppida, and can be derived from 

 Lithatractus by a spongy thickening of the cortical shell. 



1. Spongatractus pachystylus, Haeckel. 



Spongosphara .pacliystrjla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, 

 Taf. sxvi. fig. 3. 

 Cortical shell one and a half times as long as broad, with rough surface. Spongy framework 

 compact, with small meshes, about as thick as the spherical medullary shell. Polar spines very 



' S/)o?i(jfn(rac()<s = Spongy-spindle; aTroyyof. aTjaxTof. 



