Fig. 1. 
Fig. 2. 
Fig. 3 
Fig. 4 
Fig. 5 
Fig. 6. 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
PapAvIE SEED. 
Float of young Velella seen from above, ;; of an inch in length : ff’ groove in which the main 
branch of the circulatory system passes from the fixed edge of the float to the base of the keel. 
In this stage the keel is a slight ridge surmounting the single central chamber: o’o”, apertures 
opening externally from the fifth and seventh chamber on the right, and from the second and 
fourth on the left. 
The same as Fig. 1, seen in profile, showing the central chamber round which are arranged, in an 
irregular elliptical shape, the eight chambers of which the float, at this stage, is composed: ft, 
so called air tubes attached to the lower side of the float; f, groove of main branch of circula- 
tory system. 
Float of a young Velella measuring 38; of an inch. Lettering as above; 0!”’0’” 
ing externally from the ninth and sixth chambers on the right and left. 
Profile view of the float of a young Velella having eight chambers, measuring $ of an inch in 
length. Lettering as in Fig. 2, The keel, a’, rises quite perceptibly above the central cham- 
ber on a slight conical projection: a!-a8, successive chambers of the float. 
Profile view of Fig. 3. Lettering as before. The keel has greatly increased in height and the 
second line of growth is apparent. 
Float of young Velella with twelve chambers measuring } of an inch in length and haying seven 
lines of growth in the keel, which, in this stage, isa high conical lamella of entirely different 
proportions to the float than in the adult or larger specimens. 
Profile of central part of the float and keel of a young Velella with twelve chambers, but only 
four lines of growth in the keel; this is also much broader than is usually the case at this 
stage, — ;,” in length. 
Profile of young Velella with seventeen chambers in the float, measuring ;'; in length, with six 
lines of growth in the keel. 
Portion of horizontal surface of the float of young Velella with twelve chambers, showing the 
openings leading from one chamber to the adjoining ones through the common walls ; the 
opening in the last chamber opens externally. 
Showing on a somewhat larger scale the passages leading from one chamber to the other in the 
eight outer chambers of the float of the preceding figure. 
» apertures open- 
Figs. 11, 12, 13. Opening in the outer chamber of three young Velelle varying in size from + to nearl 
D ? ? P t=} y to} J 5 9 y 
Fig. 15. 
Fig. 16. 
Vig. 17. 
Fig. 18. 
Fig. 19. 
an inch in length. This opening is always in continuation of the line of openings forming the 
communication between adjoining chambers. 
Diagrammatic transverse section of young Velella with twelve chambers, showing the position 
of the keel a’, the central chamber a, and the concentric chambers a!\—a” with the groove f for 
the main branch of the circulatory system. 
Diagrammatic section of the float of a Velella with twenty-two chambers. 
The corresponding section of the opposite side showing the position of the groove f. This groove 
is only a fold of the upper walls of the chambers, and does not divide the chambers into dis- 
tinct spaces ; they form each a continuous ring. 
General view of the position of the clusters of tubules arising from the lower side of the four 
inner chambers ; some of the tubules branch, a rare occurrence in our Velella. 
Inner view of the conical part of the float of a large Velella, showing the position of the tubules 
and the corrugations and folds of the lower walls of the inner chambers; the corrugations ccc 
become less prominent in proportion to the distance from the central chamber; near the mar- 
gin of the float the walls merely bulge out and form slight undulations. 
Tubules of a large Velella which have penetrated through the so-called liver, and appear on the 
top of the liver when seen from the lower side of the cone of the float. 
View from the inside of the central part of the float showing the tubules of a young Velella 
measuring about }” in length. 
Basal part of three tubules near the attachment to the central chamber in a Velella measuring 
about 4 an inch in length. 
