BRITISH SPONGIADiE. 297 



peculiarities of the skeleton, and the size and form of the 

 spicula, closely resemble each other, but the presence of the 

 bihamate spicula in I. jugosa readily distinguishes it when 

 they are properly developed by Canada balsam. 



16. Isouictya pallida, Bowerbank. 



Sponge. When young coating, massive and sessile ; when 

 fully developed, often running into a series of short, 

 stout, inosculating branches or lobes ; each having a 

 central cloacal canal ; surface smooth. Oscula simple 

 or very slightly marginated, dispersed. Pores incon- 

 spicuous. Dermal membrane pellucid, smooth, fur- 

 nished with a unispiculous network ; spicula same as 

 those of the skeleton, but rather more slender. 

 Skeleton. Primary lines multispiculous ; secondary 

 lines often bispiculous, irregular; spicula fusiformi- 

 acerate, short and stout. Interstitial membranes. 

 Tension spicula fusiformi-acerate, slender, rather 

 numerous. 



Colour. Alive, pallid gray or cream colour. 

 Habitat. Torquay, Mrs. Griffiths. Diamond Ground 

 off Hastings. 



Examined. In the living state. 



I am indebted to the late Mrs. Griffiths, of Torquay, for 

 my first acquaintance with this interesting species. The 

 specimen is irregularly spread over a piece of rock about 

 three inches in length, and does not exceed half an inch in 

 thickness ; occasionally small columnar or conical portions 

 are thrown out laterally, which attain about half an inch 

 in height by a quarter of an inch in thickness. The sur- 

 face is smooth and undulating, and the oscula, which are 

 perfectly simple, are dispersed equally over the whole sur- 

 face and are about a quarter or half an inch asunder ; they 

 are nearly equal in diameter, which does not exceed two 



