42 THE DEVELOPMENT OF CRANGON VULGARIS. 



Fig. 40. Section through the fourth pair of appendages, stage 2>. 



Fig. 41. Obliquely lougitudinal section of stage C (Compare flg. 

 32). 



Fig. 42. Longitudinal section of stage G (constructed from two sec- 

 tions). 



Fig. 43. Longitudinal section of stage F. 



Fig. 44. Trausverse section through fourth pair of appendages of 

 stage G. 



Fig. 45. Outline of embryo at stage G. 



Figs. 46 to 49 are taken from one series, 46 being the 3rd, 47 the 7th, 

 48 the 8th, and 49 the 13th section, of stage G. 



Fig. 50. A portion of a longitudinal section of stage G^ to show the 

 mesoderm extending into the appendages. 



Fig. 51. Tip of abdoraen at about stage F showing the budding 

 cells in mesoderm and ectoderm. 



Fig. 52. Section through thorax and tip of abdoraen, stage O, show- 

 ing the germ cells. 



Fig. 53. A group of ectodermal germ cells from a surface view of 

 stage G. 



Fig. 54. Longitudinal section of stage H, constructed from three 

 sections. The liver (li) does not beloug in the plane of this section 

 but was introduced to show its position with regard to anterior and 

 posterior ends. 



Figs. 55 to 60 and 62 to 63 are taken from one series of an embryo 

 stage H. 



Fig. 55 is the 5th, 56 the 8th, 57 the lOth, 58 an enlarged portion of 

 flg. 57; 59 the 12th; 60 the 13th, 62 the 15th and 63 the 17th section. 



Fig. 61. An enlarged view of the green gland, stage H. 



Figs. 64 to 69 are from another series of sections of an embryo at 

 stage H. 



Fig. 64 is the 18th, 65 the 20th, flg. 66 the 22nd, 67 the 24th, 68 the 

 26th while 69 passes through the abdomen alone. 



Fig. 70. An enlarged view of a liver sac at stage H showing the 

 amoeboid character of the entoderm cells. 



Fig. 71. A diagrammatic representation of the relations of nerves 

 and ganglia in the brain at stage H. 



Figs. 72 and 73. Two longitudinal sections through the head and 

 brain of a free swimming zoea of Crangon. 



Fig. 74. Section through the base of the second antenna of a zoea 

 showing (eo) the external opening to the green gland. The lumen of 

 the gland did not appear in the section from which the drawing was 

 made. 



