BRITISH SPONGIAD^E. 347 



spicula is very remarkable. The skeleton spicula are 

 acerate ; they have frequently one end more abruptly at- 

 tenuated and more bluntly terminated than the other, pre- 

 senting occasionally a form intermediate between the 

 regular acerate and acuate spiculum. The spicula of the 

 membranes are also sometimes inequi-acerate, but they are' 

 more slender than those of the skeleton. The greater 

 portion of the anchorate and bihamate spicula of the mem- 

 branous structures are comparatively small, but exceedingly 

 numerous ; they are irregularly dispersed over all parts of 

 those tissues. The larger spicula of these forms are fre- 

 quently four or five times as long as the smaller ones, but 

 they are comparatively few in number. 



Montagu's observations, as quoted by Dr. Johnston in 

 his ' History of British Sponges,' is very descriptive of the 

 general character of the species. 



2. Desmaciuon Jeffretsii, Bowerbank. 



Sponge. Massive, sessile, uneven ; furnished with nume- 

 rous large and small penicellate tubular cloacae. Sur- 

 face smooth. Oscula within the cloacae. Pores incon- 

 spicuous. Dermal membrane pellucid, furnished w^ith 

 a unispiculous reticulation, spicula same as those of 

 the skeleton. Skeleton. Stout, coarse and elongately 

 diffuse ; spicula acerate, rather short and stout. Inter- 

 stitial membranes abundantly spiculous ; spicula same 

 as those of the skeleton, dispersed. Gemmules mem- 

 branous. 



Colour. — ^Dried, light buff yellow, 

 ^atoflif.— Shetland, Mr. C. W. Peach. 

 Examined. — In the dried state. 



This fine species was dredged at Shetland in 1864, by 

 Mr. J. G. Jeffreys, and preserved for me with many other 

 interesting specimens, by my friend Mr. C. W. Peach, who 

 accompanied the expedition. I have no certain information 

 regarding the correct size or configuration of the specimen. 



