328 DR. J. S. BOWERBANK ON THE SPONGIAD^E. [Mar. 18, 



radial structure prevails in patches only, and the connecting-spicula 

 are comparatively rare, and frequently in an imperfectly developed 

 condition. 



The skeleton is abundantly spiculous ; the two forms, the acerate 

 and acuate, are indiscriminately mixed in its structure ; but the 

 former prevail to a much greater extent than the latter ones. 



The short stout tension-spicula of the interstitial structures are 

 unusually large and strong ; they are very numerous, and are 

 irregularly dispersed on all parts of the membranes. The two forms 

 of stellate retentive spicula are very abundant, and are irregularly 

 dispersed over all parts of the membranes. The larger of the two, 

 the attenuato-stellate ones, are very numerous; they vary to some 

 extent in size and in the number of their radii ; the one represented 

 by fig. 11, Plate XXXI., is a very fully developed specimen. The 

 minute sphero-stellate spicula also vary somewhat in their size and 

 form, the radii in some being much more conical than in others ; and 

 they are very much more numerous than those of the larger form. 



The sponge is evidently an adult specimen, as nearly all the 

 ovaries are in the solid or exhausted condition, and very few im- 

 mature ones were observed on the more deeply seated parts of the 

 interstitial membranes. 



Geodia parasitica, Bowerbank. (Plate XXXI.) 



Sponge sessile, coating ; surface even or slightly nodose, smooth. 

 Dermal membrane translucent, furnished abundantly with minute 

 sphero-stellate spicula. Connecting-spicula attenuato-subpatento- 

 ternate, few in number. Oscula simple, dispersed (?), few in number. 

 Pores congregated, porous areas abundantly furnished with small 

 sphero-stellate retentive and defensive spicula; radii numerous, 

 short, acutely conical. Skeleton- spicula fusiformi-acerate, large 

 and stout, numerous. Interstitial membranes — tension-spicula fusi- 

 formi-acerate, small and slender ; retentive spicula small, sphero- 

 stellate, the same as those of dermal membrane, rather numerous. 

 Ovaria globose, rather depressed. 



Colour, in the dried state, light cream-yellow. 

 Hab. Unknown {Mr. Thos. Ingall). 

 Examined in the dried state. 



I am indebted to my late friend Mr. Ingall for my knowledge of 

 this species. It was originally, I believe, parasitical on the base of 

 a coral. In its present condition it consists of fourteen fragments, 

 the largest of which slightly exceeds half an inch in diameter ; when 

 entire it probably covered about 1 \ square inch ; and the thickness 

 does not appear to have exceeded \ of an inch in any part. The 

 surface has evidently been uneven, with one or more nodular 

 elevations. The surface is smooth, and there does not appear to 

 have been any large or small spicula projected beyond it. A few 

 oscula were apparent on the fragments, two of which were nearly 

 one tenth of an inch in diameter ; and on one fragment there was 

 apparently the remains of a portion of a sunken area, which may 



