20 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 81 



{Cyliconenm) apertwni than to make it a new species, even though 

 it is distinguished from the type of the species by the quite different 

 outer configuration. 



It is tulip-shaped, abruptly truncated terminally, 4 cm long, and 

 2.7 cm broad above. The gastral area is flatly exposed without 

 being depressed, entirely lacking the central cone, which is usually 

 present in the typical specimens, and somewhat flared out upward 

 and outward as a free edge. The excurrent apertures open exter- 

 nally directly on the gastral area and are fairly numerous and some- 

 what circular, and 1 mm to 4 mm in diameter. The dermal, lateral, 

 and gastral surfaces appear quite smooth and even. 



In this form the macramphidisks appear to be of two kinds. 

 One is common on the dermal membrane, measuring 220/;i to 312//, 

 in length and 108/a to 116/x. broad at the semicircular terminal disk, 

 which may be quite similarly shaped to that of H. {Cyliconema) 

 apertum solidum; while the other, in the parenchyma, usually ex- 

 hibits a smaller size, 140ju, in length, with the shaft only particu- 

 larly tuberculous in its central part, not over the entire part as in 

 the dermal larger macramphidisk. 



Acanthophores of this specimen consist of fairly large stauractins, 

 which exhibit a nearly straight and quite smooth surface except on 

 the terminal ends, the surfaces of which are roughened and some- 

 Avhat inflated. 



Table 7 may serve to show the relative proportions of various 

 spicules represented by specimens A to D from Koshiki Island, and 

 specimen E from Bungo Channel. 



Table 7. — Comparison- of specimens of Hyalonema (Cyliconema) apertum from 



Koshikl Island and Bungo Channel 



