278 A MONOGRAPH OF THE 



combined with the diffused structure of the skeleton, 

 readily distinguish this species from others nearly allied to 

 it in external characters. The gemmules are abundant 

 immediately beneath the dermal membrane of the specimen 

 from Bantry Bay ; they are round or oval, the mature ones 

 are filled with minute globular vesicles, which presented no 

 appearance of a nucleus or of granular matter within, the 

 light passing freely through their centres when viewed 

 with a linear power of 660. The average diameter of one 

 of the largest gemmules was sJjth inch in diameter, and of 

 a perfectly globular vesicle within it ^^th inch in diameter. 

 1 have dedicated this species to my friend Mr. Peach, a 

 most ardent and disinterested lover of natural history, to 

 whom I am indebted for many valuable specimens of 

 British sponges. 



3. IsoDiCTTA PERMOLLis, Bovoerbank. 



Halichoudkia oinerea, Johnston. 



Sponge. Encrusting, rarely massive. Surface smooth. 

 Oscula simple or very slightly elevated. Pores in- 

 conspicuous. Dermal membrane pellucid, aspiciilous. 

 Skeleton. Reticulations rarely more than unispicu- 

 lous ; spicula acerate, short and stout. Interstitial 

 membranes. Tension spicula acerate, slender, few in 

 number. 



Colour. — When dried, light yellow to nut-brown. 

 Habitat. — Scarborough, Mr. Bean ; Peterhead, Mr. 

 Peach. 



Examined. — In the dried state. 



I first received this sponge from Mr. Bean, of Scar- 

 borough, who pointed it out as probably a new species of 

 Halichondria. The general aspect of the species when 

 washed and dried is somewhat like that of H. panicea 

 when thinly spread over a stone or shell, but the surface 



