374 S. I. Smith — Earty Stages of the American Lobster. 



fourth and fifth segments (phite XVIII, fig. 7, one of the legs of the 

 third segment, enlai'ged 20 diameters) are proportionally lai'ger than 

 in the adult, the terminal lamella' esi)ecially being much longer and 

 furnished with very long jjlumose and jointed set^e (plate XVIII, 

 fig. 7a, enlarged 100 diameters). 



The telson (plate XVIII, fig. 4, enlarged 20 diameters) is nearly 

 quadrangular, as wide at the extremity as at the base, and the pos- 

 terior margin is arcuate, but does not extend beyond the prominent, 

 spiniform lateral angles, and is furnished with long plumose hairs. In 

 the adult the telson is not quadrangular, but much narrowed toward 

 the extremity, which is strongly arcuate, nearly semi-circular and pro- 

 jects far beyond the small dentiform lateral angles. The lamelhe 

 of the appendages of the penultimate segment (fig. 4) are regularly 

 oval and margined with long plumose hairs, and the outer lamellje 

 have a transverse articulation near the tip as in the adult, although 

 the proximal side of this articulation is not armed as in the adult 

 with numerous slender teeth, but with only a single obtuse one near 

 the middle. In the adult the lamellae are not regularly oval but 

 broader distally and somewhat truncate at the extremities. 



In color they resemble closely the adult, but the green of the back 

 is lighter, 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 ajjpear to live a large part of the time at the surface, 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. 



Specimens in this stage vary considerably in size, and it is barely 

 possible that they represent two different molts. The following mea- 

 surements of three sjiecimens taken at difierent dates illnstrate these 

 differences in size. 



July 15. July 28. July 2U. 



Length from tip of rostrum to extremity of telson, 14-0"""- 16-2"'"- 16-8™"'- 



" of carapax to tip of rostrum, 6-8 8-2 8*4 



" "rostrum, 2-7 3-2 3-2 



Breadth of carapax, 24 2-9 3-» 



Length of propodus of anterior leg, right side, 4-2 5-3 5-4 



" " dactylus " " " " _.. 2-0 2-5 2-5 



" " propodus " " left side, 4-3 5-3 5-4 



" " dactylus " " " " ._.. 2-0 2-6 2-5 



