NOTES ON A SPECIES OF BARNACLE. 
407 
that had undergone only the first cleavage; as compared with the ovarian egg they 
were elongate, narrowed somewhat, and not much pointed at the future posterior end. 
As the embyro nauplius within is developed the egg becomes more pointed at this 
end and more square-shouldered at the other. 
To understand the arrangement of the nauplial appendages in the egg, tig. 10 
of the nauplius as just hatched should be compared with the egg-nauplius of fig. 9. 
The latter figure is a ventral view of an egg nearly ready for hatching. The entire 
second appendage with its two rami is seen (tigs. 9 and 10, II, II«, IK), but the 
third appendage (see tig. 10, III, etc.) is completely hidden in this view by the 
overlapping second. The first appendage, too, is folded behind the second so that 
only its proximal portion is seen (fig. 9, I). The oesophagus apparently arches 
over ventralward, so as to open somewhat on the ventral surface of the large “upper 
lip” (ti.l.), the oesophagus being seen in optical cross-section at oes. The large 
nauplius eye ( ic.e .) is closely approximated to the brain (cer.). At the posterior end 
the point of the dorso-caudal spine (d. c. sp.) is seen just dorsal to the caudal fork 
(cdl. f), which terminates the thoraco-abdominal region of the body. 
By selecting barnacles whose capitula are tolerably well filled with eggs, and 
teasing them on a slide, eggs are frequently found from which the nauplius is in the 
act of hatching. In several cases observed under the microscope the process was as 
follows: The appendages are pressed out against the shell, while the caudal end of the 
body is bent ventrally and anteriorly against the shell. Then while the appendages 
and body are pushed anteriorly as much as possible, the caudal fork slips posteriorly 
along the shell. These alternate movements, bracing first with the appendages, then 
