624 SAMPSON. 



EXPLANATION OF PLATE XXXI. 



Fig. I. Outline of shells I, V, and VIII, dorsal surface. 



Fig. 2. Chiton viridis, Spengler. Dorsal view after removal of the shells. 

 The shell muscles in the region of shells III (in part), IV, and V have been cut 

 on the right side along the interior limit of the attachment of the pedal muscles, 

 and turned back on the left side ; the viscera removed, showing the pedal mus- 

 cles in situ on the right side. The pedal muscles under shells IV and V on the 

 left, are in part dissected near their attachments to the shell, and turned back to 

 show the relations of the muscles to one another. The muscular cushion, dorsal 

 to the right apophysis of V, has been partly removed, to show more clearly the 

 region of attachment of the anterior group of pedal muscles under that shell. 



Fig. 3. Diagram of the anterior end of Chiton viridis, Spengler (shells I, II, 

 III, IV, apophyses of V), seen from the ventral side after removal of the viscera 

 and of the pedal and mantle muscles, showing the muscles of the shells and 

 regions of the attachments of the muscles of the foot and mantle and of buccal 

 muscles. 



Fig. II. Diagram of the muscles of the buccal mass (C. viridis, Spengler) as 

 seen from the dorsal side. The dotted lines represent the' position of the radula 

 at a lower level, beneath the radula sheath, which, in this region, is extended 

 laterally, dorsal to the cartilages. 



Fig. 12. Diagram of the muscles of the buccal mass (C. viridis, Spengler) as 

 seen from the ventral side. 



Fig. 13. Diagram showing approximately the relations among the attach- 

 ments of the pedal muscles to the shells. 



