1872.] DR. J. S. BOWERBANK ON THE SPONGIAD^E. 119 



one of the best-developed ones in situ measured ygVo inch in length, 

 while a simple bihamate one of an average size measured 55^ inch 

 in length. The skeleton-spicula are large and strong, and frequently 

 exceed -^ inch in length ; the shafts of the recurvo-ternate ones are 

 quite as long as those of the skeleton-spicula, but very much less in 

 their diameter. A very few porrecto-ternate spicula were detected ; 

 and these were very small, and were imbedded irregularly among the 

 interstitial membranes. The interstitial membranes are abundantly 

 supplied with the same forms of retentive spicula that abound in the 

 dermal membranes, and they have also a considerable number of 

 very slender fiexuous tension-spicula. 



The most distinctive specific character in this sponge is un- 

 doubtedly the minute bihamate spicula so abundant in the dermal 

 and interstitial membranes ; but it must be remembered that they 

 require a power of six or seven hundred linear to render them di- 

 stinct to the eye in situ when mounted in Canada balsam, and that 

 when viewed in water they are totally obscured by the sarcode in 

 which they are imbedded. 



Tethea ingalli, Bowerbank. 



Sponge sessile, spherical or oval. Surface variable, from smooth 

 to strongly papillated ; papillae either acutely terminated or abruptly 

 truncated. Oscula and pores inconspicuous. Dermal rind thick, 

 furnished with innumerable, closely packed, large, subsphero-stellate 

 spicula ; radii acutely conical. Dermal membrane crowded with 

 minute clavate subsphero-stellate spicula. Skeleton — radial fasciculi 

 large and numerous, polyspiculous, emanating from a spherical poly- 

 spiculous centre ; spicula fusiformi acuate, large, and long ; apices 

 frequently bluntly terminated. Interstitial membranes — tension-spi- 

 cula of the same form as the skeleton ones, but smaller and slender ; 

 retentive spicula attenuato-stellate ; radii minutely and entirely spi- 

 nous, numerous. Gemmulation external. 



Colour in spirit deep orange or dull red. 

 Hab. Fremantle, Australia (Mr. George Clifton). 

 Examined in the wet condition from spirit and from saturated salt 

 water, 1855. 



I am indebted to my late friend Mr. Thomas Ingall for my first 

 acquaintance with this very interesting species. He presented to 

 me a small dried specimen less than an inch in diameter, labelled 

 " locality unknown." On examining and describing the sponge I 

 obtained from it the type forms of the spicula represented in plate 

 25. figs. 12 and 14, 'Philosophical Transactions,' 1858. 



I subsequently received from my friend Mr. George Clifton, of 

 Fremantle, Australia, a jar full of these sponges preserved in spirit ; the 

 whole of them were in very fine condition. They varied in size from 

 one about 9 lines in diameter to that represented in Plate V. fig. 1 1 . 



The normal form appears to be globular, but subject to very con- 

 siderable variations. Among the eighteen specimens in my posses- 

 sion, some are nearly spherical, while others are much taller than 



