_ 
S. I. Smith— Early stages of the Lobster. 403 
longer than the external maxillipeds. The pediform branch is, 
owever, somewhat stouter than in the outer legs, and subcheli- 
form. The legs of the second and third pairs (fig. D) are simi- 
lar to the first but not as stout. The legs of the fourth and 
fifth pairs are still more slender, and styliform at the extremity 
as in the adult. 
The exopodal branches of all the legs and of the external max- 
illipeds are quite similar, and differ very little in size. In life, 
while the animal is poised at rest in the water, they are carried 
horizontally, as represented in figure B, or are curved up over the 
carapax, sometimes so as almost to cover it. The cireu- 
lates rapidly in these appendages, and they undoubtedly serve, 
to a certain extent, as respiratory organs, as well as for locomo- 
tion. By careful examination, small —— were found rep- 
e Didninen! is slender, the second to the fifth segments 
each armed with a large dorsal spine curved backward, and with 
the lateral angles produced into long spines, and the si 
segment with two dorsal spines. The proportional size and the 
outline of the last segment is shown in figure B; its posterior 
margin is armed with a long and stout central spine, and each 
side with fourteen or fifteen plumose spines or setse, which are 
articulated to the margin. 
Second Stage.—In the next stage the larve have increased 
somewhat in size, and the abdominal legs of the second to the 
fifth segments have appeared. The rostrum is much broader, 
and there are several teeth along the edges. The basal segments 
of the antennule have become defined, and the secondary — 
lum ‘has appeared but is not subdivided into segments. 
antennz and mouth organs have undergone but slight changes. 
he first thoracic legs are proportionately larger and stouter 
* The number of branchi i ids, in the American lobster is 
twenty on each side: A aiagis Sis Oke ae ae second maxilliped, three well- 
ral maxilli 
the 
max w. en (Lectures on the Anatomy of 
in als, 2d ed., p. 322) and Edwards (Hist. nat. des Crust, 1, 
ie the whole number on each side as twenty-two, although Edwards 
nd volume of the same work, under rus, p. 333, 
