PLATE LXXXIII. 275 



lias satisfied me tliat I was iu error in describiiig it as 

 a Hymeuiacidon. It, therefore, becomes necessary to 

 add slightly to the specific description of the sjionge 

 described as a Hymeniacidon, and the foUovfing will bo 

 its description as a Microciona. 



Sponge coating, surface corrugated, slightly hispid. 

 Oscula simple, dispersed : submarginated, slightly 

 fringed. Pores inconspicuous. Dermal membrane 

 pellucid, abundantly spiculous ; spicula acuate, long 

 and slender; inner surface furnished with numerous 

 stout angulated, equi-anchorate, retentive spicula. 

 Skeleton. Columns long, slender, and fiexuous, occa- 

 sionally branching : spicula attenuato-acuate, basally 

 spined, long and stout, occasionally subclavate ; spines 

 rather stout and small. Internal defensive spicula 

 attenuato-acuate, entirely spined ; short, occasionally 

 subclavate ; spines large and long. External defensive 

 spicula acuate, like those of the dermal membrane. 

 Spicula of interstitial membranes acerate, long and 

 slender, sometimes fiexuous, numerous. Retentive 

 spicula angulated, bidentate, equi-anchorate, rarely 

 tridentate, large and stout, exceedingly numerous. 



For the general description of the sponge I must 

 refer the reader to vol ii, page 198, ' Mon. Brit. Spon- 

 giadge.' 



MiCEOOiONA PEAUDATOR, Boiverbank. 



Plate LXXXIII. 



Sponge massive, sessile, parasitical on fuci, or zoo- 

 phytes, surface uneven, pustulous. Oscula simple, dis- 

 persed. Pores inconspicuous. Dermal membrane 

 abundantly spiculous ; tension spicida same as those 

 of the skeleton, irregularly fasciculated or dispersed ; 

 fasciculi broad and flat, multispiculous ; retentive 

 spicula bidentate equi-anchorate, minute, not very 

 numerous. Skeleton, columns diffuse, long and very 

 irregular ; spicula fusiformi-acerate, short and stout. 

 Internal defensive spicula attenuato-acuate, variable 



