Vlll 



THE VOYAGE OF H.M.S. CHALLENGER. 



1. Esperiadfe. 



2. Desmacidonidffi. 



Order 3. Arenospongia. 



Family 1. Xenospongiadce, 



Subsection 2. Acanthospongia. 



Order 4. Hamispongia. 



Families — 

 3. Hamacanthidee. 



4. Gelliadse. 



L PteronemadsB. 



2. Lanuginellidse. 



3. EuplectelladEB. 



4. Hyalotliaumadae. 



Order 5. Coralliospongia. 



Families — 



5. Macandrewiadse. 



6. Farreadge. 



7. Dactyloealycidfe. 



8. Aplirocallistidae. 



9. Corbitellidfe. 



10. Askonematidse. 



IL Carteriadse. 



12. Axidae. 



1. Geodiadfe. 



2. Placospongiadae. 



3. Tethyadse. 



Order 6. Spliserospongia. 



Families — 



4. Donatiadse. 



5. Theneadee. 



6. Lophurellidae. 



7. Casuladse. 



8. ChondrilladK. 



9. AncorinidEe. 



1. Granfciadae. 



Section B. Potamospongia. 

 Family 1. Spongilladse. 

 Subclass 2. P. Calcarea. 



Families — 

 2. AlcyonceUidee. 



3. Aphroeerasidaj. 



Yet in spite of its cumbersome and largely artificial character, good features in 

 this classification are not wanting ; the best, perhaps, being that the Keratosa are here 

 already included amongst the Silicea, a step which has been fully justified by recent 

 research. To Gray also is due the credit of having appreciated the value of spicular 

 forms as a means of distinguishing genera. Of Gray's families the following belong to 

 the Monaxonida : — 



Clialinidx. 



PhaheUiadx. 



Halichondriadx. 



Polymastiadai. 



OpMstospongiadee. 



Suberitidx. 

 Raph iophoridx. 

 Clioniadse. 

 Xenospongiadx. 

 Esperiadx. 



Desmacidonidx. 

 Hamacanthidx. 

 Gelliadx. 

 Spongilladx. 

 1 Axidx. 



