Fig. 55. Section near the anterior end of the mesonephros, where the genital sack is completely formed.
Fig. 56. Section somewhat further back, shewing the mode of formation of the genital sack.
Fig. 57. Section posterior to the above, the formation of the genital sack not having commenced, and the genital ridge with primitive germinal cells projecting freely into the body-cavity.
Fig. 58A. 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, shewing the vasa efferentia and the longitudinal canal at the base of the mesorchium. The kidney ducts have been cut open posteriorly to shew the structure of the interior.
Fig. 58B. Inner aspect of the posterior lobe of the testis from the same example, to shew the vasa efferentia forming a network on the face of the testis.
Figs. 59A and B. Two sections shewing the structure and relations of the efferent ducts of the testis in the same example.
Fig. 59A. Section through the inner aspect of a portion of the testis and mesorchium, to shew the network of the vasa efferentia (nve) becoming continuous with the seminal tubes (st). The granular matter nearly filling the vasa efferentia and the seminal tubes represent the spermatozoa.
Fig. 59B. Section through part of the kidney and its duct and the longitudinal canal (lc) at the base of the mesorchium. Canals (sc) are seen passing off from the latter, which enter the kidney and join the uriniferous tubuli. Some of the latter (as well as the seminal tubes) are seen to be filled with granular matter, which we believe to be the remains of spermatozoa.
Fig. 60. Diagram of the urinogenital organs of the left side of an adult female example of Lepidosteus 100 centims. in length. This figure shews the oviduct (od) continuous with the investment of the ovary, opening at od´ into the dilated part of the kidney duct (segmental duct). It also shews the segmental duct and the junction of the latter with its fellow of the right side to form the so-called bladder, this part being represented as cut open. The kidney (k) and lymphatic organ (ly) in front of it are also shewn.
Plate 40.