98 PLATE XXXIX. 



irregular nodular masses near its base. The oscula of 

 the large fistula are disposed on its inner surface, a few 

 minute ones are discernible on the basal nodules. The 

 sponge has apparently been based on a facus, part of 

 ^yhich remains at (a). The figure is half the natural 

 size. 



Fig. 2. — Another case in which the sponge has 

 assumed the fistulous form and developed two fistulse 

 in conjunction. Natural size. 



Kg. 3. — A case in which the sponge, based on a 

 small univalve shell (&), is developed in a massive 

 state in the form of an irregular upright column, 

 the oscula, as usual in the massive forms of the 

 sponge, being dispersed on the external surface. 

 Natural size. 



Fig. 4. — A specimen based on a solid irregular sur- 

 face; small nodular masses are projected from the 

 upper surface, on each of which one or more oscula are 

 developed. Natural size. 



Fig. 5. — An irregular nodular mass pendant from a 

 slender stem of a fucus (c), which it entirely surrounds, 

 the nodules being developed equally on all sides, each 

 being supplied with one or more simple oscula. 

 Natural size. 



Fig. 6. — Two of the skeleton spicula X SO linear, 

 exhibiting their variation in size, the larger one being 

 the most numerous. 



