Bull II S F. C. 1895. The American Lobster. (To face page 208 ) 



Plate H. 



Cut 27. — Surface view of embryo, show- 

 ing buds of first pair of antenna? and 

 clouds of in-wandering cells. Tbe lat- 

 ter extend in great cumulus-like folds 

 and surround large masses of yolk with 

 tbin layers of cells. Embryo about 9 

 days old. August 6, 1891. 29 diameters. 

 In cuts 25-33 tbe eggs were fixed with 

 hot water and Mayer's picro-sulpburic 

 acid, and stained in Kleinenberg's hsemo- 

 loxylon or Grenadier's borax-carmine. 



Cut 28. — Surface view of embryo, show- 

 ing buds of first pair of antennas and 

 of mandibles. Tbe stomodaeum is 

 present in form of a small transverse 

 pit, on tbe level of a line drawn 

 through tbe posterior margins of the 

 antennary buds. Tbe outlines of the 

 masses of yolk-cells appear much 

 more circumscribed than in the earlier 

 stage shown in cut 27. Embryo 9 to 

 10 days old. August 5, 1891. 29 dia- 

 meters. 







Cut 29. — Surface view of early egg- 

 nauplius embryo, showing buds of 

 the first and second antenna? and 

 the mandibles. Mouth or opening 

 of stomodaeum distinct; in-wandering 

 cells beneath the thoracic abdominal 

 plate shaded dark. The yolk-cells are 

 still further circumscribed to outward 

 appearance, having wandered far into 

 the egg. Optic disks more clearly de- 

 fined. Embryo about 10 days old. 29 

 diameters. 



Cut 30. — Surface view of egg nauplius, 

 slightly older than that shown in cut 29; 

 second antenna? bifid; labrum and tho- 

 racic abdominal fold present; embryo 

 about 11 days old. July 12. 29 diame- 

 ters. 



In cuts 25-30 surface-cells are roughly 

 indicated only in the immediate region 

 of the embryo. 



Drawn by F. H. Herrick. 



