50 



THE SPONGES. 



rays are 24 fi long; terminal rays 20 /x long; terminals 10-15 in a cluster; 

 clusters intermediate in relative width between Fig. 3, Plate 5, and Fig. 6, 

 Plate 4. 





Caulophacus, sp. 



Plate 5, Fig. 7 



At Station SJflJf, the lower part of a stalk belonging to a species of 

 Caulophacus, apparently not C schulzei, was taken. The stalk (Fig. 7, Plate 

 5), which is attached to the root spicules of Hyalonema, is firm, hard, and 

 of a dark-brown color. The length of the fragment is 40 mm., the diameter 

 of the upper broken end 4 mm. The axial cavity is very small, about 

 0.75 mm. in diameter. The base is an irregular mass elongated in the 

 direction of the Hyalonema spicules, round which it has grown. Some of 

 the Hyalonema spicules remain in situ, while others have been pulled out, 

 leaving their impressions upon the Caulophacus base. 



The dermal covering has been lost. Whether the few pinules and large 

 pentacts adhering to the surface belong to the specimen is questionable. 

 The diacts forming the chief support are arranged for the most part lon- 

 gitudinally, and are connected by synapticula. Scattered diacts protrude 

 more or less radially from the surface to a distance of from 1 to 4 mm. 

 The diacts taper slightly from the middle toward the ends, frequently 

 exhibit an annular thickening in the middle, which is very slight in the 

 large forms, but conspicuous in some of the smaller, and end in smooth 

 pointed extremities. The diameter of the larger spicules is 24-30 /x, the 

 length reaching at any rate 4 mm. 



At the same station, two other Caulophacus stalks of a somewhat differ- 

 ent appearance were dredged. Only the diact skeleton remains. One of 

 the stalks is remarkable for its thickness, having a diameter at one end of 

 13 mm., the axial cavity being about 2 mm. wide and filled with mud. 







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