TABLE OF CONTENTS. 



PAGE 



Preface, ............ 1 



Introduction, . . . . . . . . . . . .5 



Methods of Examination, .......... 5 



Families of Keratosa, .......... 6 



Bathymetrical Table, .......... 9 



General Eemarks on the Organisation of the Deep-Sea Keratosa, . . . .11 



Individuality and External Form, . . . . . . . . .11 



Histology, ........... 13 



Canal-System, . . . . . . . . . . .16 



Skeleton, ............ 17 



Description of Genera and Species, ......... 23 



Family I. Ammoconida3, . . . . . . . . . .23 



Genus 1. Ammolyntlms, . . . . . . . . .27 



Genus 2. Ammosolenia, . . . . . . . . .29 



Genus 3. Ammoco?iia, ......... 30 



Family II. Psamminidse, . . . . . . . . . .32 



Genus 4. Psarnmina, ......... 34 



Genus 5. Holopsamma, ......... 38 



Genus 6. Psammopemma, ......... 40 



Family III. Spongelidse, .......... 42 



Genus 7. Cerelasma, .......... 45 



Genus 8. Psammophyllum, ......... 49 



Family IV. Stannomidae, . . . . . . . . . .54 



Genus 9. Stannophyllum, ......... 60 



Genus 10. Stannariam, . . . . . . . . .69 



Genus 11. Stannoma, ......... 72 



Appendix, ............ 75 



1. Symbiotic Hydroida living in the Deep-Sea Keratosa, . . . . . .75 



2. Classification of Sponges, . . . . . . . . .82 



3. Eelations of the Keratosa to the other Sponges, . . . . .85 



4. Position of the Sponges in the Animal Kingdom, ...... 90 



