426 Dr. A. Krohn on the Development of the Cirripedia. 
lopment during my residence in Madeira. It is probably the 
young of a Balanide. 
In the older larvee of this kind (fig. 1) the anterior body is of 
considerable size, and the carapace is furnished at the anterior 
margin with two moderately long horns, and -at the posterior 
margin with two spines directed obliquely upwards, which are 
wanting in younger larve. The caudiform appendage is armed, 
about halfway to its apex, with four lateral spines of consider- 
able size arranged in two pairs, and is a good deal thicker than 
the spinous process, especially in its anterior incrassated half. 
In still further advanced larve the carapace appears enlarged 
and much arched. 
One day a larger and still further developed larva of the same 
kind was captured; its close examination gave the following 
results :—The carapace was now so far changed from its former 
state, that it extended further down, and thus enclosed the body 
on both sides. The caudiform appendage appeared strongly 
inflated in its anterior longer portion, reaching somewhat beyond 
the above-mentioned pairs of spines. On the lower surface of 
this portion six pairs of processes, arranged close together in a 
row, could be distinguished through the skin; each of these con- 
sisted of a comparatively long peduncle and of two short branches 
terminating in rounded ends, issuing from it. Close behind 
the last pair, another much shorter process, with two projections 
similar to the branches of the longer processes, shone through 
the skin. Both the projections, as well as the above-mentioned 
branches, appeared to be set with thin offshoots or filaments, 
which were recognized as the rudiments of so many sete. 
With regard to the signification of these processes I could not 
long remain in doubt; they were evidently the swimming feet 
in course of development, and the base of the caudal process the 
subsequent Cypris-like form. It followed, therefore, that the 
whole inflated part of the caudiform appendage was to be re- 
garded as the rudiment of the future thorax. On each side, in 
the same line with the original simple eye, now become larger 
and enveloped by a very dark pigment, a roundish organ was 
distinguished, containing several scattered deposits of reddish- 
yellow pigment. The opinion forced itself upon me at once that 
these two structures could only be the rudiments of the compound 
eyes, which indeed was soon confirmed, as I succeeded in ob- 
serving the gradual conversion into the Cypris-form in the same 
larva. 
On the third day after the capture of the larva, I saw the 
carapace prolonged so far backwards as to form a roof over the 
entire anterior portion of the caudiform appendage. The simple 
eye had become still larger, whilst the pigment-deposits in the 
a a i 
