S. I. Smith — Early Stages of the American Lobster. 369 



in the second stage, while the dactylus itself is relatively longer, but 

 is terminated by a shorter stylet. 



The posterior legs (plate XVII, fig. V, terminal portion of one, 

 enlarged 40 diameters) have changed precisely in the same way as 

 those of the fourth pair. 



The abdomen is armed with the same number of dorsal spines as 

 in the first and second stages, but they are all much smaller than 

 in the second stage. The lateral angles of the second to the fifth 

 segments project in sharp angular teeth, which are much shorter and 

 broader than in the earlier stages and project obliquely backward and 

 downward. 



The telson (plate XIV, fig. F, enlarged 15 diameters, a, one of the 

 plumose seta3, enlarged 75 diameters, and plate XVIII, fig. 3, enlarged 

 20 diameters) is of nearly the same form as in the second stage, but 

 is proportionally much smaller — although absolutely fully as large — 

 considerably broader at base, and the setae and spines are very much 

 smaller. The natatory legs of the second, third, fourth, and fifth 

 segments (plate XVIII, fig. 6, one of the legs of the third segment, 

 enlarged 30 diameters) have increased much in size, the lamellae are 

 fully twice as long as in the second stage, are somewhat lanceolate in 

 form, and the margins of the distal half show a slight indication of 

 segmentation and are furnished with very short rudimentary setae 

 clothed with very short hairs (fig. 6a, enlarged 100 diameters). 



The appendages of the penultimate segment (plate XVIII, fig. 3, 

 enlarged 20 diameters) are well developed, although relatively smaller 

 and otherwise quite diiferent from those of the adult. The outer 

 lamella is broad ; rudely oval, wholly without a transverse articula- 

 tion near the extremity, and the outer margin is naked and neai-ly 

 straight for two-thirds its length, then obliquely truncated at a slight 

 angle and continuous in a regular curve with the j^osterior and inner 

 margins, and clothed all the way, except near the base of the inner 

 side, with long plumose setse (plate XVIII, fig. 3a, enlarged 50 diam- 

 eters) articulated to the margin but apparently not divided into seg- 

 ments like the seta3 of the exopodal branches of the cephalothoracic 

 legs. The inner lamella is a little smaller than the outer, more regu- 

 larly ovate, and margined all round, except near the base, with 

 plumose setae like those upon the outer lamella. 



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. 



