Parker. — Metridium marginatum. 



PLATE III. 



All the specimens shown on this plate, except those represented in Figure 15, had 

 each two complete oral disks and two distinct oesophageal tubes, 



Fig. 8. Transverse section of specimen C, in which the two oesophageal tubes are 

 connected by a single membrane which reached neither the oral nor 

 the pedal disks. Collected by the writer at Wood's Hole, Mass. Male. 

 X 1.6. 



Fig. 9. Transverse section of specimen D, also shown in Fig. 4 (Plate II.). Fe- 

 male. X 2. 



Fig. 10. Transverse section of specimen E, collected by B. II. Van Vleck at Cape 

 Ann, Mass. Sex not determined. X 2. 



Fig. 11. Transverse section of specimen F, collected by C. W. Prentiss at Wood's 

 Hole, Mass. Male. X 3. 



Fig. 12. Transverse section of specimen G, collected by J. I. Hamaker at New- 

 port, R. I. Femafe. X 2. 



Fig. 13. Transverse section of specimen H, collected by R. H. Johnson at Wood's 

 Hole, Mass. Female. X 2. 



Fig. 14. Transverse section of specimen I, collected by the writer at Wood's 

 Hole, Mass. Male. X 2. 



[Specimen J, collected by the writer at Wood's Hole, Mass., was lost in an attempt 

 to rear it.] 



Fig. 15. Transverse section of a natural pair of individuals, showing their mutual 

 relations so far as positions of siphonoglyphs, etc. are concerned. The 

 two specimens, which were entirely separate, were killed and preserved 

 without being removed from the shell on which they were found. 





