jll. U.S. F.C. 



The American Lobster. (To face page 209.) 



Plate I. 



Cdt 31. — Surface view of egg nauplius, 

 showing thoracic abdominal fold. The 

 mouth, as in cut 30, is screened by the lab 

 rum, and the optic disks are more sharply 

 defined; second antenna? forked; embryo 

 about 12 days old. 29 diameters. 



Cut 32. — Surface view of egg nauplius, 

 showing parts much more concentrated 

 than in earlier stages. Antenna? exhibit 

 traces of segmentation, and the second 

 antenna? have a slender inner branch. 

 The abdomen is bifid at its extremity, 

 which nearly touches the labrum ; optic 

 disk lobular; embryo 14 to 10 days old. 

 August 14. 29 diameters. 



Cut 33. — Surface view of embryo with first 

 maxilla; budded; embryo 16 to 18 days 

 old. August 5. 29 diameters. 



In cuts 31-38 there is little attempt to 

 show more than the form of the embryo. 

 The series G to J represents the progres- 

 sive development of the summer eggs. 

 Compai'e the Eate of Development, pp. 

 55 to 57, and table 18. 



Cut 34. — Surface view of embryo, showing 

 5 pairs of post-mandibular appendages. 

 The antennae have grown obliquely back- 

 ward until they come to lie nearly paral- 

 lel with the abdomen. The telson. which 

 is now distinctly forked, partially over- 

 laps the brain. Eye-pigment not yet 

 apparent. Nearly same stage as 3 (5), 

 table 18; about 21 days old. From egg 

 killed in Perenyi fluid, August 15, 1893. 

 29 diameters. 



Drawn by F. H. Herrick. 



