82 A MONOGRAPH OF THE 



the dried sponge. In this state the dermal membrane pre. 

 sents very much the same beautifully reticulated appear- 

 ance that is so striking a character in dried specimens of 

 Halichondria panicea, and the size, number, and mode of 

 disposition of the pores closely resemble those of H.panicea. 

 I could find but one form of spiculum in this sponge, the 

 fusiformi-acuate one ; they varied considerably in size and 

 diameter. This species is the only specimen of the genus 

 I have yet seen. In treating of the generic character of 

 this sponge, I have described the peculiariliies of its struc- 

 ture so fully as to render any further description of them 

 unnecessary. Since writing the above description I have 

 obtained a second specimen from the same locality. The 

 only notable difference is in size. The basal portion is 

 irregular in form, two inches in length, and one and a half 

 in breadth, and the average thickness is about half an 

 inch. There are eighteen penicillate branches, the longest 

 of them does not exceed an inch in height from the basal 

 membrane of the sponge to its distal point, and its dia- 

 meter over the base slightly exceeded two lines. It decreases 

 gradually from the base to the apex, and terminates acutely. 

 The whole of these small branches are of the same form. 

 Towards the centre of the basal mass there are the remains 

 of several very much larger branches which have been torn off 

 slightly above the surface of the base of the sponge, the 

 wounded terminations have been covered with dermal 

 membrane, but the ends of the central columns within are 

 distinctly to be seen through the new membrane. 



There is a remarkable pecidiarity in this specimen. All 

 the small penicillate branches have the side nearest the 

 outer margin of the sponge nearly smooth, while the oppo- 

 site one abounds in mammseform tubercles from base to 

 apex ; this peculiarity of the outer surface is probably due 

 to the abrasion and pressure from other bodies which were 

 growing around it. 



