4 J. G. WALLER ON A NEW BRITISH SrONGE 



what at first sight would appear to he indiscrimination ; you may- 

 trace the bihamate spicules interlocking with each other, here and 

 there held and hooked by the fluke of an anchorate form, and the 

 more rarely observed bihamate reversed or sigmoid spicule may be 

 seen twining about one of the skeleton, helping to hold on the 

 membranes as well as to keep them together. (Vid. pi. I., fig. 5, 6). 

 The reproductive organs at present remain unknown, as I am not 

 sure if the object seen in some of my preparations are other than 

 small masses of sarcode. None of the so-called gemmules have been 

 found in any of the genus except 31. armata. 



There are a greater variety of spicula in this species than in any 

 of its class, reminding one very much of those in Halichondria in- 

 crustans, to which the bihamate forms seem to make an alliance. The 

 latter are most abundant in those areas of the dermal membrane 

 which lie between the projecting apices of the skeleton columns, when 

 they sometimes interlace with each other in a curiously compact 

 manner, and it is probable that here the pores would be found, but I 

 could not perceive them. 



Having thus given a general description of this most interesting 

 species, it is now necessary to give it a name. Of course this is pro- 

 visional, in case it may already have been described by another, or 

 may be amongst those thirty or forty additions which our lamented 

 friend Dr. Bowerbank had made since the publication of his third 

 volume of the " Spongiadaa." Already, indeed, was this example 

 packed with others to be sent for his inspection, when his death 

 occurred. The name I propose has reference to its structural 

 differences which the bihamate spicule gives us, viz., Microciona 

 bihamigera. 



Following Dr. Bowerbank's formula, the Sponge may be thus 

 tabulated : — Sponge, coating, thin ; colour, when alive, olive green ; 

 dry, a paler tint of the same. Surface smooth when alive, in the dry 

 state somewhat hispid. Oscula dispersed, but sometimestwo together. 

 Pores inconspicuous. Dermal membrane thin, pellucid, spiculous. 

 Spicula cylindrical, each end abruptly pointed, slender ; retentive 

 spicula bihamate, contort and sigmoid, very numerous ; also triden- 

 tate, palmate, equi-anchorate, and a few bidentate equi-anch orate 

 large and small dispersed. Skeleton columns long and sometimes 

 branched. Spicula acuate, spinous, spines more pronounced at the 

 base ; defensive spicula the same ; also shorter ones attenuato- acuate, 



