

PLATE XIX 



l'\c. 7~\. — Diagram of heart, etc., of normal trout embryo 

 (p. 12). bettering as in Fig. 75. Above s.v. is the 

 common opening of the anterior jugular veins. For 

 general references see under PI. I. fig. 1. 



Fig. 74. Diagram of the heart, etc., of the double 

 monster (Class III.) illustrated in PI. II. fig. 7, which see 

 for general references. Lettering as in Fig. 75. 



Fig. 75.— Diagram of the heart, etc., of a double monster 

 belonging to Class IV.. i.e. with union in pectoral region, 

 the adjacent pectoral fins being present but united (p 



/ . Ventricle. 



A u. Auricle. 



SI'. Sinus venosus. 



/'r '. DUfct of L'uv 1 . 



/' . Inner or adjacent ducts of 1. 1 



VJ. Jugular vein. 



I '■ . Cardinal vein (posterior). 



( - ". Inner or adjacent cardinal ve 



Fig. 76. — Diagram illustrating the Wolffian duct and 

 urinary bladder in a normal trout embryo (p. 12). Letter- 

 ing as in Figs. 77-S1. For references see under PI. I. fig. !. 



FIGS. 77-81. — Diagrams illustrating the arrangement of 

 the Wolffian ducts and bladders according to the different 

 types described on pp. 21-23. It will be noted that the 

 ducts which associate themselves in pairs with the bladders 

 nearly always consist of the right duct of one embryo and 

 the left of the other. Fig. 80 is an exception, am! Fig. 81 

 an example of pure ventral union (p. 23). 



BL. Bladder. 

 /'/ . Uladder formed by the inner or adjacent pair .>i 



Wolffian ducts. 

 1 1 'D, Wolffian ducts. 

 II /''■'. Wolffian ducts belonging to one of the tw.i. 



of the figures. 

 WD,!'. Wolffian ducts belonging to the other twin 11 1 I 

 of the figures. 

 Int. Intestine. 

 /. . Re mm. 

 /'. Vent. 

 P. Urinary pore. 



