STRUCTURE AND DEVELOPMENT OF LEPIDOSTEUS. 
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PLATE 25. 
Figs. 47 A, B, C. Figures of adult brain. 
Fig. 47 A. From tlie side. 
Fig. 47 B. From above. 
Fig. 47 C. From below. 
Fig. 48. Longitudinal vertical section through the eye of an embryo, about a week 
after hatching, showing the vascular membrane surrounding the vitreous 
humour. 
Fig. 49. Diagram showing the arrangement of the vessels in the vascular membrane of 
the vitreous humour of adult eye. 
Fig. 50. Capillaries of the same vascular membrane. 
Fig. 51. Transverse section through anterior part of trunk of an embryo on the ninth 
day after impregnation, showing the pronephros and pronephric chamber. 
Fig. 52. Transverse section through the region of the stomach of an embryo 15 millims. 
in length, shortly after hatching, to show the glomerulus and peritoneal 
funnel of pronephros. 
Fig. 53. Transverse section through posterior part of the body of an embryo, about a 
month after hatching, showing the structure of the mesonephros, the spiral 
valve, &c. 
PLATE 26. 
Figs. 54, 55, 56, and 57 are a series of transverse sections through the genital ridge 
and mesonephros of one side from a larva of 11 centims. 
Fig. 54. Section of the lymphatic organ which lies in front of the 
mesonephros. 
Fig. 55. Section near the anterior end of the mesonephros, where the 
genital sac is completely formed. 
Fig. 56. Section somewhat further back, showing the mode of formation 
of the genital sac. 
Fig. 57. Section posterior to the above, the formation of the genital sac 
not having commenced, and the genital ridge with primitive 
germinal cells projecting freely into the body-cavity. 
Fig. 58 A. View of the testis, mesorchium, and duct of the kidney of the left side 
of an adult male example of Lepidosteus , 60 centims. in length, showing the 
vasa efferentia and the longitudinal canal at the base of the mesorchium. 
The kidney ducts have been cut open posteriorly to show the structure of 
the interior. 
3 L 
MDCCCLXXXII, 
