21 '2 I'LATE LXXlV. 



Haliciiondkia expansa, Bowerhank. 



Plate LXXIV. 



Sponge compressed, expanding laterally ; parasitical. 

 Surface smootli and even. Oscula simple, minute, 

 dispersed. Pores inconspicuous. Dermis furnished 

 with a stout, iiTegular network ; rete composed of 

 broad, flat, polyspiculous fasciculi; spicula fusiformi- 

 cylindrical ; terminations incipiently spinous, spines 

 very minute ; tension spicula acerate, long an d slender, 

 frequently flexuous ; basal terminations incipiently 

 spinous, few in number ; retentive spicula bidentate 

 inequi-anchorate and dentato-palmate inequi-aucho- 

 rate, minute, and few in number. Skeleton rather 

 compact ; rete variable, containing from one or two to 

 five or six spicula. Spicula fusiformi-acuate, rather 

 short and stout, incipiently entirely spinous, base, pro- 

 minently spinous. Interstitial membranes pellucid ; 

 tension and retentive spicula same as those of the 

 dermal membrane, few in number. Gemmules mem- 

 branous, asjDiculous. 



Colour. — In the dried state dark brown. 

 Habitat. — Skye ; Rev. A. M. Norman. 

 Examined. — In the dried state. 



The form of this sponge is very like that of a longi- 

 tudinal section of an hour-glass, witb a conical base in 

 addition. It is one inch and three quarters in height, 

 and three quarters of an inch at the two points of 

 greatest expansion, and in no part does it exceed the 

 eighth of an inch in thickness. It is parasitical on the 

 remains of a small sertularia. The oscula are very 

 minute, and they appear to be nearly, if not all, on one 

 of the broad surfaces of the sponge, and the pores 

 appear to occupy the other surface. The two sur- 

 faces, therefore, vary considerably in their reticular 

 characters ; that of the oscular surface being very 

 much more diffuse and irregular than the porous one. 

 The Ijroad flat rete of the latter one is very character- 



