364 *S'. I. Smith — Early Stages of the American Lobster. 



and arrangement of the spines being almost exactly the same, while 

 the articulations between the segments seem to be more distinctly 

 marked. The exognathus has increased Aery slightly in length, and 

 the extremity shows a slight approach to the flagelliform character 

 in the increased length of the rudimentary seta?, though there is still 

 no segmentation even at the tip. The epignathus (plate XVI, fig. 

 10, enlarged 40 diameters) has increased very little in size, but shows 

 a very slight rudiment of a branchial appendage as a minute lobe on 

 the inside near the base (fig. 10, c). 



The endognathi and exognathi of the external maxillipeds are as in 

 the first stage, except that the endognathus is a little more slender and 

 the terminal segment proportionally a little longer. The epignathus 

 and the three branchial appendages have increased very much in size, 

 the latter being elongated and the edges distinctly crenulated, but 

 the epignathus still somewhat sack-like and entirely without hairs. 

 These appendages are in exactly the same stage of development as 

 those upon the legs, and as represented in the figure of one of the 

 legs of the second pair (plate XVII, fig. 2, b, c, enlarged 20 diame- 

 ters). 



The anterior cephalothoracic legs (plate XVII, fig. 10, distal por- 

 tion of one, enlarged 20 diameters) are proportionally much larger 

 than in the first stage, and have become truly cheliform. The propo- 

 dus is projjortionally much longer than in the first stage, is armed 

 only with very short spines, and the digital portion is nearly as long 

 as the basal, and its tip is incurved and terminates in a short and slen- 

 der nail. The dactylus is very slightly longer than the digital por- 

 tion of the propodus, is shaped very much like it, and has apparently 

 some power of prehension with it. The exopodus is larger, having 

 increased in proportion wath the other legs. The epignathus and the 

 three branchial appendages are like those of the external maxillipeds. 



The second and third pairs of legs (plate XVII, fig. 2, one of the 

 second pair, enlarged 20 diameters) are alike and have increased con- 

 siderably in length. The spines upon the propodus are shorter and 

 the digital portion is more elongated, slightly incurved, and ter- 

 minated by a short nail. The dactylus is more slender, much longer 

 than the digital portion of the propodus, and terminates in a spini- 

 form stylet nearly as long as the dactylus itself, but considerably 

 shorter than in the first stage. The exopodus, epipodus, and the 

 branchial appendages are like those of the anterior legs. 



The fourth pair of legs have increased in length proportionally with 

 the second and third pairs, the spines upon the distal extremity of 



