1895.] MAIiFORMATIONS AMONGST FISHES. 429 



Bibliography. 



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2. T. Baer. — " Ueb. doppelleibigen Missgeburteu." Mem. de 



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 pt. 2, 184.5, p. 79. 



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Bd. ii. p. 61. 



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Brocbet." Ann. des Sci. Nat., Zool. ser. 4, t. xx. p. 177. 



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Poissons." Mem. de la Soc. Philomatb. 1888. 



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EXPLANATION OF PLATE XXV. 



Fig. 1. Head of trout-embryo, showing third median eye. 



2. Head of trout-embryo, showing additional, metlian, pair of eyes. 



3. Fission to region of pectoral fins. The left eye of the right fish is absent. 



4. Fission to beyond posterior border of yolk-sac. The cephalic ends are 



twisted so as to lie venter to venter. 



5. Fission with subsequent union of the caudal ends, which overlap one 



another. The tail-fins are double. 



6. Parasitism. The specimen is seen from the ventral aspect and the 



parasite projects from the left side of the autosite as a pointed process. 

 a, remains of yolk-sac; b, circular patch of pigment representing an 

 eye. 



