BRITISH SPONGIAD^. 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 /. jugosa readily distinguishes it when 

 they are properly developed by Canada balsam. 



16. IsouiCTYA PALLIDA, Bowerlanlc. 



Sponge. When young coating, massive and sessile ; when 

 fully developed, often running into a series of short, 

 stout, inosculating branches or lobes j 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 



