386 THE VOYAGE OF H.ISLS CHALLENGEE. 



Species 3. Hyalonema tenuc, n. sp. 



With narrow oval oscular aperture. The parenchyma contains small weakly 

 developed oxyhexacts wth smooth curved rays, and also somewhat larger forms with 

 thin straight smooth vays. The large amphidiscs have campanulate terminal umbels 

 with twelve to thirteen lancet-shaped rays. The dermal pinuli have somewhat long 

 smooth liasal rays, and a long, very thin radial. East of the mouth of the Rio de la 

 Plata, 1900 fathoms. 



Species 4. Hyalonema robustum, n. sp. 



The parenchyma contains small oxyhexacts with smooth or slightly roughened curved 

 rays. Besides these somewhat larger oxyhexacts occur with spinose straight rays. There 

 is a characteristic occurrence of unusually large, approximately spherical amphidiscs, in 

 which the hemispherical terminal umbels almost, or actually meet one another in the 

 middle. They consist of eight, or less frequently as many as twelve broad paddle-shaped 

 rays. The dermal pinuli have short, thick, rough, basal rays, and a long club-shaped, 

 but at the same time pointed radial ray with moderately short lateral spines. West of 

 the North Pacific, 2300 fathoms. 



Genus 2. P/ieronema, Leidy. 



The basal terminal surface of the round, goblet- or cup-shaped, thick-walled body bears 

 a broad root-tuft, not always sharply marked off. The lateral surface of the body also bears 

 projecting tufts of spicules. The circular oscular margin is surrounded (with the probable 

 exception of one species) by a cuflp-like freely projecting collar. The parenchyma of the 

 body contains uncinates. Each spicule of the root-tuft bears on its lower end a bidentate 

 anchor. The marginalia and pleuralia end externally in a club-shaped swelling. 



Species 1. Pheronema annw, Leidy. 



An egg-shaped body which is somewhat truncated both at its superior narrower and 

 inferior broader pole. The gastral cavity is cylindrical, about half the length of the 

 body, and with a flat floor. The broad basal tuft consists of numerous individual tufts 

 about half the length of the body. Slender tufts of spicules project radially in irregular 

 distribution from the lateral surface of the body. At the somewhat rounded oscular 

 margin there seems to be no special wreath of spicules. The parenchyma contains small 

 oxyliexacts sparsely beset with lateral spines. The large amphidiscs have campanulate 

 terminal umbels with eight broad lancet-shaped rays, and a thick knolibed axial lieani. 



