384 WHEELER. 
DESCRIPTION OF PLATE XxX. 
Doryphora decemlineata. 
Fic. 83. Portion of cross-section through a basal abdominal segment of an em- 
bryo somewhat younger than that represented in Fig. 74. @7, amnion; ev/, entoderm; 
ect, ectoderm; ¢, tracheal invagination; g/, ganglion; ms¢, Mittelstrang; sv, somatic 
mesoderm; s/z, splanchnic mesoderm; cé, cardioblasts. 
Fic. 84. Transverse section through middle of abdomen of embryo, Fig. 74. gn, 
sexual organ; mg, Malpighian vessel; remaining references same as in Fig. 83. 
Fic. 85. Cross-section through metathoracic segment of an embryo considerably 
older than Fig. 74. /z, lateral nerve trunk; af, appendage; sv, serosa; ad, fat cells; 
a, amnion cells entering the yolk at 4; remaining letters the same as in Fig. 83. 
Fic. 86. Cross-section through mesothorax of an embryo after the formation of 
the heart, 4¢. Asp, thickening of ectoderm which secretes the metathoracic hatching- 
spine; c/\, first cuticle shed by the embryo; cm, longitudinal commissures between 
two thoracic ganglia; f, furca; 7, point of attachment of muscles to the furca; ms/, 
muscular tissue; remaining letters as in preceding figures. 
Fic. 87. Cross-section through caudal plate of embryo before the closure of the 
anal end of the gastrula, w. <¢, cell about to wander through the blastopore into the 
amniotic cavity; sd, mass of cells which will form the mesoderm as soon as the blas- 
topore closes; evz/, cells imperfectly differentiated from those of the mass, 7zsd, which 
are to give rise to the entoderm; vz, yolk nucleus; @, amnion; 57, serosa. 
Fic. 88. Cross-section, more highly magnified than the preceding, through the 
caudal plate of an embryo somewhat younger than that of Fig. 73. The blastopore 
has closed, and the depression « marks the beginning of the proctodzal invagina- 
tion; Z is the line, unusually distinct in the section figured, separating the mass of 
mesoderm cells (msd@) above it from the smaller mass of entoderm cells (ev?) below 
it; ¢ 0, v, degenerating nuclei which pass from the entoderm into the yolk; y, yolk 
nucleus. 
Fic. 89. Frontal section through the cardioblasts (cd) of an embryo in the same 
stage as Fig. 84; cb, row of cardioblasts; ecd, msd, ent, germ layers; ad, fat cells. 
Fic. 90. Portion of a cross-section through the lower part of the dorsal yolk of 
an embryo in the stage of Fig. 74. ch, chorion; sv, serosa; am, amnion; do, amniotic 
dorsal organ; m, amniotic nuclei degenerating; v, yolk nucleus. 
Fic. 91. Frontal section through the meso- and meta-thoracic ganglia of the em- 
bryo, Fig. 74. cm, longitudinal commissures; ccm, cross-commissures ; n\, anterior 
nerve trunk; #2, posterior nerve trunk; ov7/, outer neurilemma; znr/, inner neu- 
rilemma. 
