80 A MONOGRAPH OF THE 



of such a length as to be easily disposed of symmetrically, 

 but in the armature of the distal bull), the spicula appro- 

 priated are large and generally in perfect condition. The 

 spinulate ones frequently have their bulbous bases outward, 

 and the same reversals of position occurs with the acuate 

 forms. 



These peculiarities of position are strong evidence of 

 their extraneous character. Their attachment to the heads 

 of the sponge would otherwise lead us to suppose they 

 were all really secreted by the animal, as their attached 

 extremities are enveloped by the membranous and sarcodous 

 tissues of the sponge, and these are continued around them 

 for some distance upwards, while thin webs of dermal 

 membrane connect the attached portion of the spicula with 

 each other just as if they were the proper secreting organs 

 of the spicula they envelop. These peculiarities of habit 

 and structure are similar to those prevailing in Bysidea 

 with the difference that one is productive of fibrous tissue, 

 while, on the other, the development is tubular. 



I could not detect any peculiarities in the basal portion 

 of the sponge, such as exist in that of H. Tumanoiolczii, 

 and the sponge is larger in all its parts than in that species ; 

 the branches were from two to three times the diameter, 

 and the bulbous heads were in the proportion of four and 

 a half to two, or two and a half the size of those of H, 

 Tumanowiczii. 



The acquisition of this species has thrown more light on 

 the peculiarities of structure and habit of the genus Haly- 

 physema, and it is a question whether in a future re-arrange- 

 ment of the sub-orders these sponges should not be removed 

 from Sub-order I to Sub-order II ; the essential base of 

 the skeleton being membranous. 



