PLATE XLIV. 



Fig. I. S^irordi'svcrntca {Fabricius), p. 2^^. Back view of a double operculum 

 plate showing the primary and secondary ones before separation. 



2. Hyalopomatopsis occidentalis sp. nov., p. 229. Operculum, in which a 



delicate yellowish (horny ?) cap is partially defined. 



3. Pomatoccros triquetra (Linne), p. 222. Operculum plate from a speci- 



men from Denmark in the Yale University Museum. 



4. Hyalopomatopsis occidentalis sp. nov., p. 229. Another operculum, less 



convex on top, showing conspicuous air-bubble. 



5. Spirorbis s>'p.} Operculum showing a large calcareous plate, from an 



animal forming a tube which resembles that of Spirorbis spirorbis 

 (Linn^) from Greenland. As the collar setae could not be found, 

 the species remains undetermined. It may be the very young of one 

 of the larger forms. 



6. The same operculum in another position. 



7. Protula media Stimpson, p. 228. Reproduction of Professor Verrill's 



figure published in Transactions of the Connecticut Academy, 1874. 



8. Hyalopotnatopsis occidefitalis fi^. nov.,]). 22<). Operculum from a full- 



grown animal, showing distinct central cavity and canal in peduncle, 

 on the end of which alg^ are growing. 



9. Outline sketch of the anterior portion of a young animal. 



10. Spirorbis sp. ? Operculum of animal from Alaska. 



11. Spirorbis validus Verrill, p. 249. Back view of a calcareous plate. 



12. The same plate in another position. 



13. Opposite view to fig. 11. 



14. A double plate showing primary one about splitting away. Both 



specimens were on Buccinum from the Grand Banks, in 36-51 

 fathoms. 



15. Spirorbis sp.} Front view of fig. 5. 



16. Spirorbis verruca (Fabricius), p. 247. Opposite view to fig. i. 



17. Spirorbis variabilis sp. nov., p. 238. Operculum with minute proto- 



zoans on end, side view. 



18. Spirorbis rtigatiis sp. nov., p. 243. Front view of operculum showing 



plate. 



19. Side view. 



20. Spirorbis morcki Levinsen, p. 240. Operculum showing large cal- 



careous cap, from specimen from off the eastern coast of New Eng- 

 land, in 1 10-120 fathoms. 



21. Back view of another operculum, showing eggs. 



22. Eupomatus humilis sp. nov., p. 235. Operculum greatly enlarged. 

 All figures by the author, X 3O) except 3, X 90; 7> X X' ^"'i 22, X 278. 



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