310 



ERYLUS CALICULATUS. 



Var. cidaris. 



Cortical armour composed chiefly of aspidasters. Rhabd megascleres 

 chiefly sharp-jjointed amphioxes; 440-650 by 8-12 /<. Rhabd-clusters 125- 

 180 [L long. Microrhabds gradually and sharply pointed, more or less centro- 

 tyle; 32-50 by 2-4.5 /l Triaenes; rhabdome 180-190 // long; cladome 300- 

 440 11 broad. Acanthtylasters with two or more rays; 12-31 p. in diameter. 

 Oxyasters 8-14 /i in diameter. Aspidasters 65-75 by 62-69 by 5-7 ji; average 

 proportion of length to breadth to thickness 100 : 96 : 9.2. 



South coast of Molokai. 



The structure of the canal-system and spiculation f)f these sponges clearly 

 show that they belong to Erylus. They differ considerably from all the species 

 of this genus i)reviously descrilxnl, by the nearly circular shape and the small 

 size of their aspidasters and other characters. Their nearest ally is the species 

 here described as Erylus caliculatus. By its shape being caliculate, by its micro- 

 rhabds being am])histrongyle instead of amphiox, by its aspidasters being larger, 

 relatively much thicker, and partly reniform in shape, and by its spicules gener- 

 ally being larger antl much stouter, this sponge differs from E. rotundus to 

 such an extent, that it must be considered specifically distinct from it. 



Plate 5, figs. G-IO, 2-1, 25, 29; Plate G, figs. 1-1,3, 19-23, 2G, 28, 29; Plate 7, figs. 11-15, 31-41, 74, 77, 



78, SO; Plate 8, figs. 1-12, l.''>-2f). 



I establish this species for a specimen obtained on the northeast coast of 

 Hawaii (Station 4062). The name refers to its caliculate shape. 



Shape and size. The sponge (Plate 5, fig. 29) appears as a broad, low, 

 truncate, inverted cone. It is 33 mm. high. The base of the cone, which forms 

 the upper side of the sponge, is irregularly oval in outline, depressed in the 

 middle, 47 mm. long, and 36 mm. broad. Its elevated margin is rounded, about 

 6 mm. thick, and partly divided into lobes. The base of attachment, which 

 corresponds to the truncate summit of the cone, measures 30 by 18 mm. The 

 surface is uneven and covered with shallow grooves, 0.5-1 mm. broad. These 

 grooves are particularly well marked on the protruding marginal lobes. Nu- 

 merous small circular pores, \\\) to 0.3 mm. in diameter, are scattered over the 

 sides of the sponge. Apertures occur also on its depressed upper face, but 

 these are not so numerous and less uniform in size than those on the sides. 

 The largest of these apical apertures, which I am inclined to consider as oscules, 

 measure 1 mm. in diameter. The margin is free from pores. 



