STRUCTURE AND DEVELOPMENT OE LEPIDOSTEUS. 
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Fig. 66. Viscera of an adult female, 100 centims. in length, showing the alimentary- 
canal with its appended glands in natural position, and the air-bladder with 
its aperture into the throat ( a.b ',). The proximal part of the duodenum and 
the terminal part of the intestine are represented as cut open, the former 
to show the pyloric valve and the apertures of the pyloric caeca and bile duct, 
and the latter to show the spiral valve. 
This figure was drawn for us by Professor A. C. Haddon. 
PLATE 28. 
Fig. 67. Transverse section through the tail of an advanced larva, showing the neural 
and haemal processes, the independently developed interneural and inter- 
haemal elements ( i.s .), and the commencing dermal fin-rays (d.f.). 
Fig. 68. Side view of the tail of a larva, 21 millims. in length, dissected so as to show 
the structure of the skeleton. 
Fig. 69. Longitudinal horizontal section through the vertebral column of a larva, 
5'5 centims. in length, on the level of the haemal arches, showing the inter¬ 
vertebral rings of cartilage continuous with the arches, the vertebral 
constriction of the notochord, &c. 
Figs. 70 and 71. Transverse sections through the vertebral column of a larva of 
5’5 centims. The red represents bone, and the blue cartilage. 
Fig. 70. Through the vertebral region, showing the neural and haemal 
arches, the notochordal sheath, &c. 
Fig. 71. Through the intervertebral region, showing the intervertebral 
cartilage. 
Figs. 72 and 73. Transverse sections through the trunk of a larva of 5'5 centims. to 
show the structure of the ribs and haemal arches. 
Fig. 72. Through the anterior part of the trunk. 
Fig. 73. Through the posterior part of the trunk. 
PLATE 29. 
Figs. 74-76. Transverse sections through the trunk of the same larva as figs. 72 
and 73. 
Fig. 74. Through the posterior part of the trunk (rather further back 
than fig. 73). 
Fig. 75. Through the anterior part of the tail. 
Fig. 76. Bather further back than fig. 75. 
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