EXPLANATION OF PLATES. 393 



PLATE LI. 

 PAIRED EYES OF CYCLOSALPA PINNATA, Chain Form. 



Figure 1, a transverse section of the posterior part of the ganglion, showing the 

 posterior pair of small eyes, ey. X 240 diameters. 



Figures 2 and 3, transverse sections of the dorsal part of the ganglion, showing 

 the dorsal pair of small eyes, ex. X 240 diameters. 



Cf . also Figure 8, Plate XLIX. 



CYCLOSALPA PINNATA, Solitary Form. 



Figure 4, a longitudinal, vertical section of the ganglion of a young embryo, 

 showing how the dorsal part of the adult ganglion is formed from the dorsal wall of 

 the originally thin-walled neural canal. X 265 diameters. 



Figures 5 and 6, transverse sections through the rudiment of the optic ridge, e, 

 and the ganglion with adjacent parts. Figure 5 shows the two anterior limbs of the 

 eye ; Fig. 6 its posterior curved portion, x 157 diameters. 



Fig. 7, a transverse section through the ganglion, eye, and adjacent parts in an 

 advanced embryo, showing also the disk-like enlargements of the lateral tubes of 

 the subneural gland. The section cuts the two anterior limbs of the eye. x 157 

 diameters. 



Figure 8, a transverse section through the ganglion and the anterior limbs of the 

 eye. Adult. X 157 diameters. 



Figure 9, a more enlarged drawing of one of the limbs of the eye shown in Fig. 8. 

 X 495 diameters. 



PLATE LII. 

 SALPA CYLINDBICA, Solitary. 



Figure 1, a transverse section of the ganglion, eye and adjacent parts. The sec- 

 tion cuts the posterior curved part of the eye. X 240 diameters. 



Figure 2, a similar section cutting the two anterior limbs of the eye. X 157 

 diameters. 



Figure 3, a more enlarged drawing of one of the two limbs of the eye shown in 

 Fig. 2. X 495 diameters. 



Chain Form. 



Figure 4, a longitudinal, vertical section of the ganglion, eyes, ciliated funnel 

 and adjacent parts, showing the two eyes, ex (the smaller) and e' + e" (the larger). 

 X 98 diameters. 



Figures 5-7, transverse sections of three regions of the larger eye. The small 

 lateral lobes of the eye are seen at a. Fig. 5 represents the more posterior section. 

 X 240 diameters. 



Figure 8, a transverse section of the ganglion, through the small eye, ex, show- 

 ing also the slight ventro-lateral outgrowths from the ganglion, b. X 240 diameters. 



Figure 9, a transverse section of the dorsal part of the ganglion, through the 

 center of the smaller eye, showing its inner vation, on. 



Figures 10 and 11, transverse sections of the parts adjacent to the ganglion, 

 showing the well-developed left lateral tube, d, and the rudimentary right lateral 

 tube, d', of the subneural gland. X 180 diameters. 



Figure 12, a longitudinal, vertical section of the ganglion and the adjacent parts, 

 showing a portion of the left lateral tube of the subneural gland. X 180 diameters. 



