BRITISH SPONGIADjE. 75 



Captain Thomas, of the Hydrographical Survey, sent me 

 from Orkney. These peculiarities also agree with those 

 which I have described as characterising the Rev. A. M. 

 Norman's specimen from Guernsey. 



None of these specimens had elongated fistular cloacal 

 appendages, with a truncated distal termination, which are 

 so abundant on the Lame Lough specimens, while in the 

 latter a few of the short mammaeform organs are found at 

 the extreme margin of the sponge. In the structural 

 characters of the young specimens we also find slight 

 differences arising from immaturity. Thus the spicula in 

 the young sponge are neither so long nor so stout as those 

 of the mature ones, and the spinulate characters are not 

 quite so fully developed as in those of the Lame Lough 

 specimens, but in every other respect there is no essential 

 structural difference. I have thought it important to 

 mention these differences existing between the immature 

 and the mature specimens, that hasty observers may not 

 be led to believe them to be distinct species. The incre- 

 ment of the sponge is effected by a progressive extension 

 of the dermal crust of the basal mass. On removing a 

 small portion of this part, and mounting it in Canada 

 balsam, it presented very much the same appearance as 

 that of a small portion of an adult fistula. A series of 

 parallel bundles of spicula in the direction of right angles 

 to the margin of the sponge, connected by secondary 

 skeleton fasciculi, in the areas of the reticulations of which 

 the pores were seated. 



