







PLATE XX 



Fig. 82. — Lateral view of the composite auditors sac 

 present in the angle between the twin heads of a double 

 monster belonging to Class II.. i.e. with union of the twin 

 brains at the medulla oblongata. Description on p. 17, 

 and other references under PI. I. fig. 6. 



I tr. ft 



a.sc. An anteriorly placed semicircular canal. 



p. !C. A posteriorly , . 



>"]<;. S3. — Diagram of head-kidney of 'a normal trout 

 embryo (p. \z). 



(',L. Glomerular tuft of vessels. 

 I \fferent in 

 V. Efferent yi ssel. 



apsule of glomerulus. 

 I i>. Commencer :ian duct JS-7 



HK. Coils of Wolffian duct in head-kidney. 



F)G. 84. — Composite head-kidney in a double mon- 

 strosity, of the type described on p. 14. Lettering as in 

 ■ . Two glomerular tufts are present in a cavity 

 ded into three chambers. 

 0. Mesial chamber. 

 FIG. 85. — Head-kidney in a double monstrosity of same 

 general type as last, but here the glomeruli have not united 

 er, though the adjacent halves of each give origin to 

 no Wolffian ducts or only to a short blind one. Lettering 

 as in Fig. 82. 



Figs. 86 and 87. —Head-kidney glomeruli of other two 

 double monstrosities showing a degree of-duplicity greater 

 than that illustrated in Fig. 85. A blind sacculated tube 

 conies off fiord the middle compartment of the composite 

 glomerulus and represents united adjacent Wolffian ducts. 









