1910.] NATURAL SCIENCES OF PHILADELPHIA. 501 



Fig. 4. — Spirorbis serratus sp. nov. Two calcareous plates of operculum; upper 



one tilted to show posterior basal serrations ; lower separate shield-shaped 



frontal plate. 

 Fig. 5. — Spirorbis formosus Bush. Side view of operculum with two complete 



calcareous cylinders. 

 Fig. 6. — Spirirbis nudus sp. nov. Side view of operculum. 

 Fig. 7. — Spirorbis mutabilis Bush. Side view of animal taken from tube and 



stained to show position of eggs (e), protozoans, etc., cover the operculum; 



«, back view of an operculum filled with eggs; b, front view of another 



operculum, the calcareous plate is dislodged; c, views of another operculum; 



d, back and side views of collar seta. 

 Fig. 8. — Paravermilia bermudensis Bush. Side view of operculum of type, the 



tip broken off; a, abdominal seta; b, edge of thoracic uncinus; c, collar 



seta. 

 Fig. 9. — Paravermilia intermedia Bush. Side view of operculum; a, abdominal 



seta; b, edge of thoracic uncinus; c, back view of seta from 2d segment. 



All the figures are camera-lucida drawings by the author. A No. 3 objective 

 was used for the opercula, with the exception of fig. 1, where an inch objective 

 was used. No. 7 objective was used for the setse. 



