922 BULLETIN OF THE 
that a detailed description of them would be superfluous. In specimens 
8 mm. or 9 mm. long the transverse suture of the exopod of the swim- 
merets (Fig. 15, XIX, re) has not yet appeared. As in full-grown 
individuals, the inner side of the tip of tho styliform appendage of the 
preceding abdominal members (Fig. 26, s) is furnished with microscopic 
curled hairs (Fig. 27), whose function I cannot imagine. They occur in 
both sexes. The internal branch of the second pair of abdominal mem- 
bers in mature male specimens presents a second slender inner append- 
age (Fig. 28, s) fringed with hairs on its outer margin. The small 
endopod of the first pair of abdominal appendages, moreover, is differ- 
ently shaped in the two sexes. In the male, the distal third widens and 
trends slightly inward ; on the inner margin, near the base, are some 
long sete; the distal portion bears short, plumous sete. In the female, 
the endopod narrows gradually from its root to the tip, and is fringed 
at the end and along the internal border by long feather-like hairs. 
In the above-described series of larval forms I have never obtamed 
the third stage directly from the second, but with this exception I have 
actually reared in confinement each successive stage from its predecessor, 
from the first to the sixth inclusive, 
The only larva known to me on this coast liable to be confounded 
with Palcemonetes is that of Virbius zostericola Smith. In specimens 
6.5 mm. long, still in the Schizopod condition, the carpus of the second 
pair of feet is already tri-articulate, and the setze of the telson, form of 
the antennal scale, and other characters serve to distinguish it from the 
young Palemonetes. 
It appears, from what precedes, that Palemonetes issues from the 
egg in the zoéa-form, i. e. provided with a pair of compound eyes, 
two pairs of antenna, two pairs of maxillæ, and three pairs of swim- 
ming-feet, the future maxillipeds. Behind the third pair of, swim- 
ming-feet are, the rudiments of the following two pairs of append- 
ages in the shape of double sac-like structures. No gills exist, the 
aration of the blood being accomplished through the general integu- 
ment, and especially under the sides of the carapace, by means of a cur- 
rent of water maintained, as in the gill-bearing adult, by the constant 
motion of the broad external plate of the second maxilla, The abdomen 
is wholly devoid of appendages, and the telson is not clearly marked 
off from the sixth abdominal segment. 
As development proceeds, the rest of the thoracic legs are unfolded in 
succession from before backward. The only break in the regular order 
of succession is caused by the unfolding of the last pair carher than the 
