BRITISH SPONGIAD^E. 109 



required a microscopic power of about 300 linear to define 

 them well. I could not detect the oscula in any of the 

 specimens I examined. 



Among the specimens of British sponges formerly be- 

 longing to Colonel Montagu, but now in the possession of 

 Professor Grant, there is a dwarf specimen of this species, 

 but it is not the type one figured by Montagu in vol. ii, 

 pi. 5, of the f Wernerian Memoirs.' 



6. Dictyocylindrus aculeatus, Bowerbank. 



Halichonduiata aculeata, Johnston. 



Sponge. Sessile, rising from numerous small slightly 

 expanded bases, branching and anastomosing. Sur- 

 face uneven, abundantly furnished with large spicula 

 projecting at nearly right angles to the axis. Oscula 

 and pores inconspicuous. Dermal membrane pellucid, 

 somewhat stout. Spicula. Of the skeleton ; acuate, 

 large, long and flexuous. Of the membranes; fusifor- 

 mi-acerate and occasionally fusiformi-acuate ; slender 

 and flexuous. Internal defensive spicula attenuato- 

 acuate, slightly but entirely spined, rare. Gemmules ? 

 Spherical or slightly oval, smooth, opaque, from once 

 to twice the largest diameter of the skeleton spicula. 



Colour. Purple-gray when dried. 



Habitat. Scarborough, Mr. Bean. 



Examined. In the dried state. 



This interesting little species was found at Scarborough, 

 many years since, by my indefatigable friend, Mr. Bean. 

 He had labelled it Halichondria aculeata in his cabinet. I 

 have therefore adopted that appropriate specific name. 



The height of the sponge does not exceed half an inch, 

 and its numerous primary branches are based on small 

 Balani; they are all nearly equal in height, and at their 

 distal extremities there are occasionally branches thrown 

 off in a horizontal direction, which seems to indicate that 



