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



oxyhexasters with short principal and long terminal rays, and by discohexasters. Of these 

 the one set have moderately short principals and four to six long S-shaped terminals, while 

 the others have long substantial principals and numerous short, somewhat convex, 

 terminals. The dermal and gastral skeletons contain compact j)entacts and four-pronged 

 scopulas, in which the rough, slightly curved, or almost straight rough prongs are equipped 

 with slight terminal knobs. Besides the dermal pentacts, there are bundles of fine 

 radially disposed oxydiacts projecting beyond the bounding surface. Japan. 



Genus 2. Cyrtaulon [Volvulina, 0. Schmidt), n. gen. 



The variously shaped body is traversed by very irregular canals. The dictyonal 

 framework forms an irregular feltwork of plates and strands. The parenchyma contains 

 peculiar spicules, which may be regarded either as scopulse with tuft-like or radially- 

 disposed prongs bearing terminal discs, or better, as discohexasters with one much elon- 

 gated and strongly developed principal ray, and five others always much shortened, and 

 bearing tufts of terminal rays. 



Species 1. Cyrtaulon sigsbeei (0. Schmidt). 



A variously shaped, not unfrequently goblet-like form, in which the wall consists of 

 an irregular feltwork, with cavities in which the apertures, both on the external and on 

 the internal bounding surface, are covered with skin. The dictyonal framework itself 

 consists of tubercled beams, in which here and there, especially near the surface of the 

 sponge, the nodes of intersection are thickened and beset with wart-like prominences. 

 The parenchyma contains uncinates with central thickening and modified scopulse, or 

 discohexaster forms with numerous thin prongs radiating out from the terminal node of 

 the stalk, and bearing marginally toothed terminal discs. The dermal skeleton consists 

 of medium-sized pentacts and hexacts, with typical scopulse with knobbed prongs. 

 AntUle Islands, 100 to 300 fathoms. 



Species 2. Cyrtaulon solutus, n. sp. 



The only specimen as yet known is a cylindrical body within a ca^dty in a stone. 

 The supporting framework is irregular with strands and plates. The dictyonal network 

 exhibits small superficial tubercles, but no marked thickening of the nodes of intersection. 

 The genericaUy characteristic modifications of scopulse or discohexasters, which occur in 

 the parenchyma instead of the typical hexasters, exhibit on the knobbed and thickened 

 end of the (otherwise pointed) stalk nvimerous thin radiating prongs or terminal rays, with 

 small convex, marginally toothed terminal discs. Besides the pentacts of the dermal 



