Sponge from the I'liiUppine Islands. 379 



head (including tlic arms) being about as broad as long, viz. 

 l-150tli of an inch (fig. 9) — that is, about three or four times 

 less in diameter than the thickest part of the shaft, which is 

 much nearer the free than the fixed end. 



The spicules of the latticework (fig. 2) are of three kinds : — 



1, a strong five-rayed or nail-like form, consisting of a vertical 

 shaft })uinted at one end, and carrying at the other four rather 

 long, robust, horizontal arms at right angles to the shaft and 

 to each other ; the shafts of these spicules are fixed in the 

 general sponge-mass vertically ; and the arms of each extend 

 towards, meet, and overlap those of others horizontally, thus 

 forming the square-shaped meshes of the larger latticework ; 



2, long, slender, fusiform, acerate spicules, which lie upon the 

 arms of the large nail-like forms longitudinally, and help to 

 strengthen the lines of the latticework ; 3, small crucially 

 headed spicules of the nail-like form, the shaft of which is 

 much longer than the arms of the head, and furnished all 

 round throughout the greater part of its length with long 

 spines, which are bent obliquely outwards and extend to the 

 pointed end, giving the whole a plumose appearance ; the arms, 

 which are nearly smooth, are pointed, opposite, and at right 

 angles to the shaft and to each other (fig. 8). These spicules 

 are generally found in pairs, with the shafts close together and 

 the arms obliquely crossing each other as they rest upon those 

 of the large nail-like spicules ; also throughout the areas of 

 the large meshes, where their nail-like heads are fixed in the 

 dermal membrane, with the common shaft standing outwards, 

 and the points of the arms touching those of their neighbours, 

 so as to divide the large meshes of the latticework into a 

 number of smaller ones, each of which is converted into a 

 round hole or pore by the dermal sarcode. 



But amongst the spicules of the surface must be mentioned 

 a very large, stout, acerate spicule, closely resembling that 

 found by Mr. H. J. Carter in the stem of C rater omorplia 

 Meyeri^ measuring in its average largest size about 4-12ths 

 of an inch in length by l-66th at its broadest part. It is 

 occasionally found under the arms of the large nail-like 

 spicules, but generally together Avith long slender acerates 

 (both smooth and spined), composing strong fibrous lines, 

 Avhich contribute to support the latticework and to connect 

 it with the general sponge-mass (PI. XXII. fig. 1). 



The spicules of the general structure are : — 1, large and 

 small nail-like forms, with smooth shafts and arms ; 2, long, 

 slender, smooth, fusiform acerates ; 3, the same, witii four 

 large tubercles on the middle of the spicule, or abortive rays; 

 4, long, thin, fusiform-accrate, thieklv spined throughout, the 



27* 



