Fia. 
Fic. 
Fic. 
Fia. 
4. 
IPTG AMEND) WUE 
Young Velella seen in profile, measuring about ;’; of an inch in length: c, central chamber; 
1, central part of the liver in the conical part of the float; f, flexible keel formed by the free 
edge of the mantle; cp, central feeding polypite; ¢, prehensile tentacles; fp, small feeding 
polypites. 
Same seen from the lower side, with single ramifications of the liver system extending to the 
edge of the horizontal mantle. 
Somewhat younger than the preceding stage. The ramifications of the liver system are Jess 
pronounced ; the central feeding polypite is not expanded as in the other stages. 
One of the large blue prehensile marginal tentacles, ¢, of the preceding figure. 
Fies. 5, 6,7. Different stages of growth of the small feeding polypites of Fig. 3. 
Fie 
Fig. 
Fia. 
Fra. 
Fic. 
Fie. 
Fie. 
Fia. 
Fia. 
Fr. 
Fic. 
Fia 
5 Ast 
cutee 
18. 
Smallest Velella found at the Tortugas, with a hood-like free mantle, with only four chambers, 
a conical float, much like that of Pl. III, Fig. 1, in shape, surmounted by a flexible flat ellip- 
tical crest, with a large central polypite, eight large prehensile marginal tentacles, and the 
same number of small rudimentary feeding polypites. 
The same as Fig. 8, seen from above, showing the simple tubes of the liver system of that stage. 
Central polypite ofa large Velella slightly drawn in. 
Different attitude of the same. 
Basal part of the same when fully expanded. 
Distal extremity of the same when fully extended. 
Terminal part of one of the prehensile tentacles, showing the band of lasso-cells running along 
the edges. 
Somewhat more magnified view of a part of such a gentacle, showing the terminal band of 
lasso-cells. 
Pari of the base of a prehensile tentacle where the band of lasso-cells becomes broken up in 
patches. 
One of the prehensile tentacles showing the passage of the terminal band of lasso-cells into 
patches near the base. 
Young prehensile tentacle, with large patches of lasso-cells, but without a terminal band. 
Portion of proliferous polypite with young meduse buds m, and the extremity of the tubule ¢. 
Fras. 20, 21. Ramifications of the vascular system at the base of the feeding polypites on the mantle of 
Fig 
29 
asa. 
the lower side of the float. 
Enlarged view of the central feeding polypite of an adult Velella, showing the rudimentary lips 
of the actinal opening and the longitudinal rows of patches of lasso-cells 6. 
