PLATE XI. 

 Pleurobranchus agassizii MacFarland. 



Fig. 43. Shell in dorsal view, x 15. 



Fig. 44. Dorsal view of loth, nth, and I2th elements of labial 

 armature from 8th to loth rows, x 240. 



Fig. 45. Ventral view of elements of labial armature from near 

 margin of 65th and 66th rows, x 372. 



Fig. 46. Ventral view of bases of elements of labial armature 

 from middle portion. At this focus the hook and den- 

 ticles are not seen, x 240. 



Figs. 47, 48. Lateral views of isolated elements of labial arma- 

 ture, x 372. 



Fig. 49. Outermost lateral teeth of eleventh row of radula. 

 x 450. 



Fig. 50. Twenty-first and twenty-second lateral teeth of 22d row 

 of radula. x 450. 



Fig. 51. 1 6th, 17th, and i8th teeth of I9th row of radula, ob- 

 liquely from above, x 450. 



Fig. 52. ist, 2nd, and 3rd lateral teeth of I9th row of radula, 

 obliquely from above, x 450. 



Fig- 53- Ventral view of bases of iTth to 2ist lateral teeth of 

 nth row of radula. x 450. 



Fig. 54. Lateral view of glans penis and vaginal opening from 

 below, v., vaginal opening, x 12. 



