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234 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [528] 
an adult form, it would undoubtedly be regarded as a distinct genus. 
The rostrum is bifid at tip, and armed with three or four teeth on each side 
toward the base, and in some specimens with a minute additional spine, 
on one or both sides, close to the tip. The flagella of the antennulie ex- 
tend scarcely beyond the tip of the rostrum. The antennal scale is very 
much reduced in size, but is still conspicuous and furnished with long 
plumose hairs along the inner margin, while the flagellum is as long as 
the carapax. The palpi of the mandibles have assumed the adult 
character, but the mandibles themselves have not acquired the massive 
molar character which they have in the older animal. The other mouth- 
organs have nearly the adult form. The anterior legs, although quite 
large, are still slender and just alike on the two sides, while all the 
cephalothoracie legs retain a distinct process in place of the swimming 
exopodi of thelarva. The lateral angles of the second to the fifth abdomi- 
nal segments are prolonged downward into long spiniform teeth, the ap- 
pendages of these segments are proportionately much longer than in the 
adult, and the margins of their terminal lamell are furnished with very 
long plumose hairs. The lamelle of the appendages of the penultimate 
segment are oval, and margined with long plumose hairs. The terminal 
segment is nearly quadrangular, as wide at the extremity as at the 
base, the posterior margin arcuate, but not extending beyond the promi- 
nent lateral angles, and furnished with hairs like those on the margins 
of the lamelle of the appendages of the penultimate segment. 
In color they resemble closely the adult, but the green color of the 
back is ighter, and the yellowish markings upon the claws and body 
are proportionately larger. 
In this stage, the young lobsters swim very rapidly by means of the 
abdominal legs, and dart backward, when disturbed, with the caudal 
appendages, frequently jumping out of the water in this way like shrimp, 
which their movements in the water much resemble. They appear 
to be truly surface animals, as in the earlier stages, and were often seen 
Swimming about among other surface animals. They were frequently 
taken from the 8th to the 28th of July, and very likely occur much 
later. 
From the dates at which the different forms were taken, it is probable 
that they pass through all the stages here described in the course of a 
Single season. How late the young, after reaching the lobster-lske 
form, retain their free-swimming habit was not ascertained. 
The young of the different kinds of shrimp, Crangon vulgaris, Paleemo- 
netes vulgaris, and Virbius zostericola, when hatched from the egg, are free- 
Swimming animals, similar in their habits to the young of the lobster. 
In structure, however, they are quite unlike the larve of the lobster, and 
approach more the zoéa stages of the crabs, which are described farther 
on. When they first leave the. egg, they are without the five pairs of 
cephalothoracic legs, the abdomen is without appendages, and much as 
it isin the first stage of the young lobster, while the maxillipeds are 
