S. I. Smith — Early Stages of the American Lobster. 253 



ward and marked with several laro;e dendritic spots of red pigment. 

 In specimens a little further advanced (figm-e 2) the future antennula is 

 pjg, 2* slightly separated from the external 



membrane of the sack and is seen 

 forming within it, and at its tip 

 there appear to be several rudi- 

 mentary setae. 



The antennae (g, figure 1) are but 

 little larger than the antennulae and 

 are sack-like and without articula- 

 tions, but the scale and flagellum 

 are separated and bent backward, 

 the scale being represented by the 

 large and somewhat expanded lobe, 

 and the flagellum by a shorter and 

 slender lobe which arises from near the base of the scale. In speci- 

 mens a little further advanced (figure 2), the extremity of the scale 

 shows a few very short and rudimentary setae, and the flagellum is 

 tipped with three of the same character. 



The mandibles, both pairs of maxilhe, and the first and second 

 maxillipeds are not sufficiently developed to be seen without remov- 

 ing the edge of the carapax and the adjacent jjarts. By dividing the 

 embryo in two, however, removing the carapax, and viewino- the 

 parts under compression, a number of lobes corresponding to the 

 mouth organs can be seen (figure 2). The anterior of these (c, figure 

 2), apparently representing the mandible, is broad, simple and clearly 

 defined. Next are several small and indistinct lobes {d, figure 2) re- 

 presenting, probably, the maxillae. Then, a larger lobe, indistinctly 

 divided into three parts at the extremity (e, figure 2), represents the 

 first maxilliped, and a slender lobe, with the terminal portion divided 

 into two processes (/, figure 2), represents the second maxilliped. 

 The external maxillipeds (/, figure 1, and g, figure 2) are well developed 

 and almost exactly like the posterior cephalothoracic legs. Both the 

 branches are simple and sack-like, the main branch, or endognathus,f 



* Cephalic appendages of the left side of an embryo a little further advanced than 

 figure 1 , as seen under compression, enlarged 40 diameters ; a, antennula ; b, antenna ; 

 c, mandible ; d, maxilla; ; e, first maxilliped ; /, second maxilliped ; g, base of external 

 maxilliped. 



f To prevent confusion, the terms here used are the Latin forms of those proposed 

 by Milne Edwards to designate the different branches of the cephalothoracic ap- 

 pendages: endopodus, for the main branch of a leg ; exo^wdus, for the accessory branch ; 

 einjmdus, for the flabelliform appendage; and endognathtis, exognathus, and epignaihus, 

 for the corresponding branches of the mouth organs. 



