Paeker. — Metridium margiuatum. 



PLATE I. 



Reproductions of figures of double specimens from the unpublished drawings of 



Professor Louis Agassiz. 



Fig. 1, Side view of a specimen with two oral disks. The original drawing is 



marked, " Alive in Aquarial Gardens, May, 1860." Drawn by J. 



Burkhardt. 

 Fig. 2. Oral view of a partly contracted specimen with two oral disks. The two 



disks show a greater difference in size than is usual with this species. 

 Fig. 8. Oral view of what is probably the same animal as that shown in Figure 2, 



but in a more contracted state. 



The original drawings from which Figures 2 and 3 were taken were on the same 

 sheet of paper, which was marked, "Boston, Sept. 28, '47." Drawn by W. H. 

 Tappan. 



