THE SPOKGES. 87 



pretation. The terminal rays of the scopula wouhl seem to represent 

 branches of that hexact ray which lies opposite the shaft. The ray in 

 question, which would correspond to the principal ray of a hexaster, is 

 reduced to a minimum, as sometimes occurs in hexasters. Thus the whole 

 scopula corresponds, as Schulze (1887) suggests, to a diact with one long ray 

 (shaft) and one exceedingly short ray, which is produced into branches. 



The sponge here described offers many points of resemblance in habitus 

 and dictyonal framework to Sclerothaw.nus dansii Marsh., the type specimens 

 of which, owned by the Rijks-Museum in Leiden, I was permitted to ex- 

 amine. The more perfect specimen is a large and beautiful one. While 

 this specimen is bushy as Marshall (1875) states, it is nevertheless as a 

 whole compressed, one horizontal diameter of the colony being several 

 times as great as the other. The branches themselves also are in places 

 not cylindrical, but somewhat compressed. The dictyonal framework is 

 very coarsely porous as compared with the dense compact skeleton of 

 my species. 



Sclerothammis clausii contains (Schulze, 1887) the following free spicules: 

 dermal hexacts, floricorae-like hexasters, dermal scopulae, uncinates, scopula- 

 like spicules with transverse spines on the shaft. The pinules (Fig. 6, 

 Plate IX.) present in my species are very few in number, but they are 

 so peculiar that it seems likely they belong to the sponge. The oxyhex- 

 asters, oxydiacts, and spinose hexacts are present in considerable numbers, 

 and doubtless belong to the sponge. Thus there would seem to be a 

 serious difference in the matter of the free spicules between Sderothamnus 

 and Sclerothamnopsis. 



The Leiden specimens of Sclerothammis clausii were obtained from an 

 unknown locality. Steere's (Murie's) specimen came from the P!\ilippine 

 waters. The " Challenger" fragments were trawled Lat. 4° 31' 0" S., Long. 

 129° 57' 20" E., at a depth of 360 fathoms, on volcanic mud. 



