PLATE CXVIIL 



Fig. 



1. Dorsal view of Tetreres murata, Allen, from Plymouth. Slightly enlarged. 

 1 a. The same from the ventral surface. Slightly enlarged. 



1 b. Anterior end of the foregoing from the dorsum. More highly magnified. 



1 c. Ventral view of the foregoing. 



1 d. Portion of the tube. X a little more than twice. 



2. Mass of tubes of Sabellaria alveolata, L., from the Humber. Nat. size. 



3. Mass of tubes of Sabellaria spinulosa, Leuckart, from St. Andrews. Nat. size. 



3 a. Opercular crown of the foregoing. Enlarged. 



4. Lateral view of Pectinaria belgica, Pallas. Enlarged. 



4 a. Tube of the foregoing. 



5. Ordinary tube of Amjphictene auricoma, 0. F. Miiller. Rev. J. M. Anderson. 



Enlarged. 



5 a and 5 b. Tube composed of transversely arranged siliceous spicules of sponges* from 



deep water. J. M. A. Enlarged. 



6. Anterior end of Lagis Koreni, Malmgren, projecting from its tube. Enlarged. 



7. Lateral view of Amphicteis Gimneri, Sars. Enlarged. 



8. Lateral view of Samytha sexcirrata, Sars, St. Magnus Bay, Shetland. Enlarged. 



9. Lateral view of Melinna cristata, Sars. Enlarged. 



10. Lateral view of Amage auricula, Malmgren. Enlarged. 



11. Tentacle of Sabellides octocirrata, Sars, var. britannica, Mel. X oc. 4, obj. A. 



12. Dorsal view of the anterior end of Am^pharete acutifrons, Grube. Enlarged. (After 



Fauvel.) (Vide p. 66.) 



13. Lateral view of Sabellaria alveolata, L. Enlarged. 



