264 HUGH WATSON. 



Fig. 102. — x 5. A. parva; side view of radula without its muscles. 



Fig. 103. — x 6. A. dimidia; ventral view of odontophore. 



Fig. 104. — X 6. A. dimidia; side view of odontopliore without its 

 sheath. 



Fig. 105. — X 6. A. dimidia; dorsal view of odontophoral support. 



Fig. 106. — x 6. A. dimidia; side view of radula with its retractor 

 muscles. 



Fig. 107. — X 6. A. dimidia; side view of radula without its 

 muscles. 



Fig. 108. — x 4. A. burnupi; side view of odontophoral support. 



Fig. 109. — X 4. A. burnupi; dorsal view of odontopliore without 

 its sheath. 



Fig. 110. — X 6|. A. sexangula; venti-al view of odontopliore. 



Fig. 111. — X fii. A. sexangula; dorsal view of odontopliore with- 

 out its sheath. 



Fig. 112. — x 65. A. sexangula; dorsal view of odontophoral 

 support. 



Fig. 113. — x 65. A. sexangula; side view of radula with its 

 retractor muscles. 



Fig. 114. — x 6h. A. sexangula; dorsal view of radula without its 

 muscles. 



PLATE XVIII. 



Figs. 115-122. — x 55. Apera dimidia; serial transverse sections 

 through the odontophore. 



PLATE XIX. 



Fig. 123. — x 30. Apera gibbonsi gracilis; front end of radula. 

 Fig. 124.- — x 30. A. gibbonsi lupata; front end of radula. 



PLATE XX. 



Fig. 125. — x 25. Apera gibbonsi s. s.; part of radula. 

 Fig. 126. — X 25. A. gibbonsi rubella; part of radula. 

 Fig. 127. — X 127. A. dimidia; part of radula. 

 Fig. 128. — X 127. A. burnupi; part of radula. 



