PLATE VIII. (continued.) 



Fig. 104. (See explanation of Figs. 97-100.) The 113th section ; it passes through 

 the pleural ganglia and the abdominal ganglion. A large nerve con- 

 nects the abdominal ganglion with a pocket-like infolding from the 

 wall of the mantle cavity. X 100. Figure 117 (Plate IX.) shows a 

 portion of this section more highly magnified. 



" 105. (See explanation of Figs. 103, 103 a .) The 212th section; it passes 

 through the cerebral commissure. X 100. 



" 106. (See explanation of Figs. 97-100.) This section, the 122d, passes 

 through the right cerebral invagination, the right cerebral and buccal 

 ganglia with their connective, and the right visceral ganglion. It also 

 shows the left pleural and visceral ganglia with their connective. 

 X 100. 



" 107. Is a combination of two successive sections cut parallel to the sagittal 

 plane from an embryo of the sixteenth day. It shows the cerebral, 

 pedal, and pleural ganglia, with their connectives, and the otocyst of 

 the left side. The position of the pedal gland is shown by dotted 

 lines. Perenyi's fluid ; picro-carminate of lithium. X 100. 



" 108-113. See explanation of Figs. 103, 103 a . 



" 108. The 225th section of the series shows the cerebral invaginations. The 

 right one (an enlarged view of which is seen in Fig. 127) is cut length- 

 wise, it being still open to the exterior; the left one transversely. 

 The cerebral ganglia and their lateral lobes, and the buccal ganglia 

 with their commissure crossing between the radula sac below and the 

 oesophagus above, are also shown. X 83. 



" 109. The 176th section, which passes through the pedal ganglia and the ab- 

 dominal ganglion. X 83. 



" 110. The 180th section ; it shows, in addition to the organs seen in Fig. 109, a 

 small portion of the left visceral ganglion and the otocysts. 



" 111. The 186th section ; it passes through the pedal ganglia, a portion of the 

 pleural ganglion of the right side, both visceral ganglia, and the ab- 

 dominal ganglion. It also shows the connective from the abdominal 

 to the right visceral ganglion, and a stout nerve arising from the 

 latter, x 83. 



" 112. The 187th section shows the pedal, pleural, and visceral ganglia. X 83. 



" 113. The 194th section. This shows, in addition to the ganglia, the nerve 

 which arises from the left visceral ganglion. X 83. 





