ON THE DEVELOPMENT OF LINGULA ANATINA. 55 



cally it does not appear different from the other parts of the liver 

 (PL VIL, Figs. 91, 93, pst. dr. h.). 



The ventral lobe of the liver is faintly seen at the 5 p. c. 

 stage (PI. V., Fig. 77, vt. lv.). From this time it increases in 

 size, and by the 8 p. c. stage it (PI. VI., Figs. 83, 85, and 

 PI. VIL, Figs. 91, 93) becomes a cup-like out-bulging of the 

 liver walls, which communicates by a broad opening with the 

 stomachal cavity. The opening can readily be seen in a dorsal 

 as well as in a ventral view. As the result of a more rapid 

 growth in the posterior direction, two lateral swellings arise in 

 that part, the lobe thus assuming an inverted heart-shape. While 

 anteriorly it extends somewhat further forward than the anterior 

 cœca of the posterior dorsal lobe, posteriorly it does not extend 

 as far as the middle region of the same. Between this lobe of 

 the liver and the mid-gut a narrow space remains for the 3L 

 obliqui medli, which here freely decussate. In some, especially 

 older, larvae the epithelium between the ventral and posterior 

 dorsal lobes is found ciliated. This is the beginning of the 

 formation of the stomach of the adult. 



The mid-gut which appeared at the 4 p. c. stage as a slightly 

 concave area of the larval " stomach " (PI. V., Fig. 75, md. gt.) 

 has now attained a moderate length, slightly bending toward the 

 ventral body wall (PL V., Figs. 77-80, PL VI., Figs. 81-85, 

 and PI VIL, Figs. 91, 93, 94, md. gt.). It consists of high 

 columnar cells distinctly bearing cilia. The cells are so closely 

 apposed to one another that they appear as a group of fine 

 threads. The nuclei of these cells are situated at different levels 

 and stain so intensely that in sections they appear near the base 

 of the epithelium as a dark zone of five or six nuclei in thickness 

 (PL VIL, Fig. 93). On the ventral side the mid-gut extends 



