BRITISH SPONGIAD^. 189 



them a peculiarity in their form that I have not observed 

 before. From the obtuse base of the spiculum they con- 

 tinue of the same size for the length of six or eight times 

 their own diameter, and then suddenly commence the fusi- 

 form expansion, giving them the appearance of having a 

 handle at the basal extremity. The tension spicula are 

 very minute, and are frequently collected into groups or 

 fasciculi, which contain a considerable number. The con- 

 tort bihamate spicula are dispersed in the sarcode ; they 

 are minute, short, and if not contort would be nearly semi- 

 lunar in form. The anchorate spicula are exceedingly in- 

 teresting ; they are large and stout, the palm at one extre- 

 mity is much expanded, while that at the opposite end is 

 not produced to anything like the same degree. From the 

 constant inequality in the production of these parts of the 

 spiculum, I was led to believe that there must be some 

 peculiar arrangement of these organs, and on carefully 

 examining the inner surface of the dermal membrane, I 

 found my suspicions were correct. They are congregated 

 at distant intervals in radiating circles, containing some- 

 times not more than six or eight spicula, while in other 

 groups they are too numerous to be counted. The groups 

 are usually semi-globose, the smaller ends of the spicula 

 being based on the membrane, but occasionally they become 

 perfectly globose, the proximal ends of the spicula consti- 

 tuting the centre of the group, which then appears to be 

 entirely detached from the membrane beneath. The globose 

 congregations of spicula are not nearly so numerous as the 

 rosette-shaped ones. I could not detect any congregations 

 of these spicula on the interstitial membranes, but isolated 

 ones were occasionally found upon them. The smaller 

 variety of anchorate spicula never appear to congregate. 



The skeleton spicula are exceedingly abundant, and are 

 so massed together as to assume the appearance of large 

 fasciculi, when the membranes are presented to the eye 

 either edgeways or obliquely. 



The sarcode abounds in globular nucleated cells, which 

 have the surface granulated, or corrugated; the latter 

 appearance may probably be due to the action of the spirit 



