REPORT ON THE HEXACTINELLIDA. 381 



club-shaped sponge in the mud. The chambers are not exactly thim1)lc-shapcd, nor 

 sharply marked off from one another, but form irregular diverticula of the membrana 

 reticularis. 



Family H Y a L o N E M A T i D .E, Gray. 

 Both dermal and gastral membranes contain numerous pentact pinuli. 



Subfamily 1. Hyalonematin^, F. E. S. 



The compressed usually cup- or goblet-shaped body bears on the upper surface a 

 more or less sharply contoured round excurrent (oscular) region, and is only excep- 

 tionally split laterally. 



Genus 1. Hyalonema, Gray. 



At the lower pole of the funnel-shaped or more spherical body, there is a long, narrow, 

 sharply defined root-tuft, in which the spicules are at their lower end equipped with a four- 

 toothed anchor structure. No uncinates. The slender marginalia are superiorly pointed 

 diacts with toothed distal ray. 



Subgenus 1. Hyalonema, s. str. 



The superior aperture of the gastral cavity is covered Ijy a sieve network which 

 extends from the annular rim with its cuff-like fringe of fine marginalia, either flatly 

 over the whole gastral aperture, or sunk into a funnel-shaped depression. 



Species 1. Hyalonema sieboldii, Gray. 



The almost cylindrical, inferiorly rounded, superiorly truncate body shows at its 

 infeiior pole a twisted tuft of long spicules, almost as thick as a little finger. The 

 terminal sieve-plate exhibits a cruciate zone of imperforate skin, Ij'ing above the four 

 crossed radial septa, and bears in the middle a central cone. 



The upper portion of the root-tuft is surrounded by an encrustation of Palythoa 

 fatua, Max Schultze, and other commensal Anthozoa are seated on the external skin. The 

 parenchyma contains small oxyhexacts with straight, and others with curved toothed 

 rays. The larger amphidiscs have broad arched umbels with eight rather broad paddle- 

 shaped rays. Japan. 



