?8 THE YOUNG OF THE CRAYFISHES ASTACUS AND CAMBARUS 



PLATE IV. 



Figure 27. Outer face of left mandible of second stage. 2. A. 



28. Inner face of left mandible of second stage. 2. A. 



29. Outer face of left first maxilla of second stage. 2. A. 



30. Outer face of second maxilla of second stage. 2. A. 



31. Outer face of first maxilliped of second stage. 2. A. 



32 1 . Outer face of left second maxilliped of second stage. 2. A. 



33. Outer face of left third maxilliped of second stage. 2. A. 



34. Posterior face of left chela of second stage. 2. A. 



PLATE V. 



Figure 35. Posterior face of left second walking leg, second stage. 2. A. 



36. Posterior face of left third walking leg, second stage. 2. A. 



37. Posterior face of left fourth walking leg, second stage. 2. A. 



38. Posterior face of left fifth walking leg and pleuro branch. 2. A. 



39. Posterior face of a left pleopod of second stage. 2. A. 



PLATE VI. 



Figure 40. Dorsal aspect of living larva in the third stage in normal attitude which makes 

 the telsou fore-shortened. 290 mm., aa. 



41. Side view of living third-stage larva kept quiet by alcohol. 290 mm., aa. 



42. Dorsal aspect of the left newly expanded pleopod of the sixth segment of the 



third-stage larva. 2. A. 



43. Dorsal aspect of the tclson of third-stage larva. 2. A. 



CAMBARUS AFFINIS. 

 PLATE VII. 



Figure 44. Posterior face of fourth left pleopod of adult female. 290 mm., aa. 



45. Eggs attached to pleopod of adult female about twenty hours after being laid. 



290 mm., aa. 



4(5. Ventral aspect of posterior part of abdomen of first larva, showing attachment 

 of telson thread, the concealed sixth and free fifth and fourth pleopods. From 

 a recently hatched larva. 2. A. 



47. Dorsal aspect of telson and sixth abdominal somite of first larva twenty hours 



after hatching. 2. A. 



48. Ventral aspect of terminal middle part of tekon of first larva dissected out of 



egg-shell, showing attachment of telson thread to certain spines. 2. D. 



49. Dorsal aspect of first larva as seen in Worcester's liquid. 290 mm., aa. 



50. Right side of first larva, seen in Worcester's liquid. 290 mm., aa. 



51. Front view of eyes and rostrum of first larva, seen in Worcester's liquid. 2. aa. 



52. Pleopod covered by larvae in the first stage and 48 hours old; alive; some few re- 



moved. Camera lucida on dissecting stand, Steinheil Aplanatic, No. 9. 



53. Dorsal aspect of left antennule of first stage. 2. A. 



54. Lower face of left antenna of first stage. 2. A. 



55. Outer face of left mandible of first stage. 2. A. 



56. Outer face of left first maxilla of first stage. 2. A. 



57. Outer face of left second maxilla of first stage. 2. A. 



1 In Figs. 32 to 37 the anterior arthrobranch is dotted for distinctness. 



