[527] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 23 
Specimens in this stage were taken only twice, July 1 and 15. They 
have the same habits and general appearance as in the first stage, but 
are readily distinguished by the possession of rudimentary abdominal 
legs. In color they.are almost exactly the same, only the orange-colored 
markings are perhaps a little less intense. 
Third stage.—In the third stage (Plate IX, figs. /, F, G,) the larvie 
are about half an inch (12 to 13™™) in length, and the integument is of a 
much firmer consistency than in the earlier stages. The antennulie are 
still rudimentary, and considerably shorter than the rostrum, although 
the secondary flagellum has increased in length, and begins to show 
division into numerous segments. The antenn retain the most marked 
feature of the early stages—the large size of the scale—but the flagellum 
is much longer than the scale, and begins to show division into segments. 
The mandibles, maxillee, and first and second maxillipeds have changed 
very little, although in the second maxillipeds the extremity of the ex- 
ognathus begins to assume a flagelliform character, and the branchia is 
represented by a small process upon the side of the epignathus. The 
external maxillipeds have begun to lose their pediform character. The 
anterior legs have increased enormously in size, and those of the second 
and third pairs have become truly chelate, while the swimming exopo- 
dal branches of all the legs, as well as of the external maxillipeds, are 
relatively much smaller and more unimportant. The epipodi (fig. @) 
are furnished with hairs along the edges, and begin to assume the char- 
acters of these appendages in the adult. The branchi (fig. @) have 
developed rapidly, and have a single series of well-marked lobes along 
each side. The abdomen still has the spines characteristic of the ear- 
lier stages, though all of them are much reduced in size. The appen- 
dages of the second to the fifth segments have become conspicuous, their 
lamelle have more than doubled in length, and the margins of the ter- 
minal half are furnished with very short ciliated sete. The appendages 
of the penultimate segment (fig. /’) are well developed, although quite 
different from those in the adult. The outer lamella wants wholly the 
transverse articulation near its extremity, and both are margined, ex- 
cept the outer edge of the outer lamella, with long plumose hairs. The 
last segment is relatively smaller and more quadrangular in outline, 
and the spines of the posterior margin are much smaller. 
*The only specimens procured in this stage were taken July 8 and 15. 
In color they were less brilliant than in the earlier stages, the orange 
markings being duller and whole animal slightly tinged with greenish 
brown. 
In the next stage observed, the animal, about three-fifths of an inch 
(14 to 17™™) long, has lost all its schizopodal characters, and has assumed 
the more important features of the adult lobster. It still retains, how- 
ever, the free-swimming habit of the true larval forms, and was fre- 
quently taken at the surface, both in the towing and hand net. Although 
resembling the adult in many features, it differs so much that, were it 
