PLATE XVII. 



DiCTTOCYLIN DI!US H ISI'IJiUS, Boirrvha ll!,-. 

 Vol. ii, i>. ]0S, ' Mull. Brit. SponyKula:'.' 



Fig. 1. — Represents a specimen from tlie Diamond 

 Trawling Ground, off Hastings, in tlie condition in 

 wliicli it came from the sea. It is more tliau usually 

 branclied, and lias probably originallj^ been tvro 

 specimens united l3y approximation, and it has evidently 

 been separated for a considerable period from its 

 natural base. This species occurs in every variety of 

 form from a single stem with one or two branches only 

 up to the complex-branching specimen figured. In 

 this specimen the hispidation is very slightly apparent, 

 while in dried specimens it is abundantly visible. 

 Natural size. 



Fig. 2. — Eepresents a singular variety of tlie species 

 dredged by Mr. Jonathan Couch, of Polperro, off the 

 Dodmau in forty fathoms, October, 1866. Numerous 

 other similar specimens were obtained in the same 

 locality at the same time. Mr. Couch kindly sent 

 me three of the specimens, and in neither of tliem 

 could I detect any appearance of a basal attachment. 

 One of the specimens is considerably longer than that 

 represented by fig. 2, but the diameter of the whole 

 were as nearly as possil:»le the same, and in the liivung 

 state they were as flexible as a piece of soft Avet string. 

 Very slight indications of hispidation were visible; 

 although so different in external character, their in- 

 ternal structures were in perfect accordance. Natural 

 size in the wet state. 



Fig. 3. — One of the skeleton spicula from the 

 central axis of the sponge. X 80 linear. 



This spiculum also represents one of the external 

 defensive spicula. 



Fig. 4. — One of the internal defensive spicula. 

 X 320 linear. 



Fig. 5. — One of the tension spicula from the inter- 

 stitial membranes. X 80 hnear. 



