216 IXATE LXXIV. 



Hymeniacidon tegetbcula, Boioerhank. 

 Plate LXXIV. 



Sponge parasitical on fuci, more or less fan or cup- 

 shaped, firm and fleshy ; margins tHck and roimd ; 

 outer or convex surface smooth and even ; inner or 

 concave surface even, but somewhat corrugated. Os- 

 cula simple, dispersed. Pores inconspicuous. Dermal 

 membrane abundantly spiculous ; spicula acerate, of 

 the same size as those of the skeleton ; collected in 

 short flat fasciculi which cross each other at every jdos- 

 sible angle so as to present an irregular matted appear- 

 ance. Skeleton compactly formed; spicula acerate, 

 stout, and moderately long, rather numerous. 



Colour. — In spirit, light fawn-yellow ; dried, nearly 

 white. 



Habitat. — Jersey ; Eev. A. Norman. 



Examined. — From spii-it. 



I received several fragments of this sponge from the 

 Rev. A. M. jSTorman for examination; two of them 

 exactly fitted each other, and were evidently parts of 

 the same sponge ; the other fragments were also pro- 

 bably parts of it, but they could not be made to fit any 

 parts of the margin of the specimen formed by the two 

 conjoined pieces represented by fig. 16, Plate LXXIV. 

 The specimen thus reconstructed has a curve about 

 equal to one third of the circumference of a cup, it 

 rather exceeds two inches across, and is an inch and 

 three quarters in height at the junction of the two 

 pieces. From the well-defined approximation to the 

 fragment of a cup-shaped sponge, I should scarcely 

 have imagined it to have been parasitical on a slender 

 soft fucus if it had not been that portions of the plant 

 are protruded throiigh several parts of its surface, and 

 the flat bases of three young plants are just without 

 the dermis of the concave surface of the sponge, the 

 stems being immersed in its substance, and no other 

 evidence of attachment to any solid substance being 



