368 S. I. Synith — Early Stages of the American Lobster. 



size. The flagelliform portion is composed of the same number of 

 segments as in the earlier stages, but the plumose hairs are somewhat 

 shorter. The epignathus has increased much in size, has entirely lost 

 its sack-like character, and is furnished with a few hairs along the 

 mai'gins. The three branchial appendages have also increased much 

 in size, and are lobed along the sides. The epignathus and branchial 

 appendages are in the same stage as those upon the second pair of 

 legs (plate XVII, fig. 3, enlarged 20 diameters). 



The anterior legs (plate XVII, fig. 11, distal extremity of one, 

 enlarged 20 diameters) have increased very much in size, and begin 

 to i-esemble somewhat those of the adult, although they are still just 

 alike on the two sides, and differ very conspicuously in the form of 

 the propodus, which has the lower margin nearly straight, the upper 

 margin convex, and the fingers thus somewhat deflexed, while in the 

 earliest state of the adult form the lower margin is sti'ongly convex 

 and the fingers turned slightly upward. The endopodus reaches be- 

 yond the extremities of the other legs by the full length of the 

 propodus, is proportionally very much stouter than they, and is fur- 

 nished with only short spinules and hairs. The propodus is broad 

 and stout, the inferior margin nearly straight, and the digital portion 

 about two thirds as long as the basal and tapering to an obtuse ex- 

 tremity. The dactylus is strongly curved downward toward the tip, 

 which is slender but not acute. The exopodus is jDroportionally much 

 smaller than in the second stage, being absolutely about as large and 

 having the same number of segments in the flagelliform portion but 

 furnished with shorter plumose hairs. The epipodus and the branchial 

 appendages are like those of the external maxillipeds and have evi- 

 dently begun to perform the same fimctions as in the adult. 



The second and third pairs of legs (plate XVII, fig. 3, one of the 

 second pair enlarged 20 diameters) have increased considerably in 

 size and become truly cheliform. The inferior margin of the propodus 

 is armed only with very small spines, but there is still, as in the 

 earlier stages, a long spine armed with acute teeth, on each side at 

 the base of the dactylus, and the digital portion is nearly as long as 

 the dactylus, is minutely toothed along the inner edge and terminates 

 in a very short styliform tip. The dactylus projects only slightly 

 beyond the propodus and like it is toothed along the inner edge and 

 terminates in a slender tip. The exopodus, epipodus and branchial 

 appendages are like those parts in the anterior legs as well as in the 

 fourth pair. 



The fourth pair of legs are of the same length as the second and 

 third, the spines upon the propodus are relatively a little shorter than 



