274 PROCEEDINGS OP THE AMERICAN ACADEMY 



ling the embryonic stages of Poronotus figured in this memoir. When, 

 however, we reach the Jurassic, Cretaceous, and Tertiary, we come 

 upon types more closely allied to the older stages of our bony Fishes, 

 embryos in which an anterior dorsal is found, of which the anterior 

 part is more or less developed, as in Platax semiophorus and the like, 

 having also heterocercal tails. We also meet in these later formations 

 genera in which the fin rays of the ventrals are still excessively 

 developed, as in embryo Gadoids, and finally find the Fishes of the 

 youngest formations agreeing more closely than any of their predeces- 

 sors with the adult forms found in the seas of the present day. 



The number of scattered papers in which various young stages 

 of osseous Fishes are described is large, but, with the exception of 

 the memoirs of Sundevall, of Liitken, and of an interesting chapter 

 on Young Fishes by Giinther in his Introduction to the Study of 

 Fishes, these papers are usually limited to a single stage of develop- 

 ment. As the present communication is mainly devoted to the study 

 of young stages which have not as yet been described, I have quoted 

 only those papers which had special reference to the genera here 

 studied. I propose to incorporate the bibliography covering this sub- 

 ject with that of the Embryology of Fishes now in preparation for the 

 " Selections from Embryological Monographs " to be published in 

 vol. ix. of the Memoirs of the Museum of Comparative Zoology. 



Labrax lineatus. Bl. S^ Sch. {Roccus, Gill). 

 (Plate I. Plate II. figs. 3, 4.) 



In very young striped Bass, measuring about 3.5°^" in length (Plate 

 I. fig. 1), the eye is of a bright blue color, with an emerald green band 

 above the pupil. This, with the prominent silvery swimming bladder 

 and the long line of large chromatophores extending from the vent 

 along the base of the embryonic anal fin nearly to the extremity of 

 the body, renders it easy to recognize the young stages of the Bass. 

 All the stages here figured were collected on the surface with the tow- 

 net. The eggs I have not found. 



In the next stage (Plate I. fig. 2) the head has become proportion- 

 ally larger, the mouth is placed more anteriorly, and the embryonic 

 caudal rays are also more prominent. Tlie muscular bands, the brain 

 as well as the stomach, are colored a light yellowish-brown. 



In the next stage (Plate I. fig, 3) the head is comparatively still 

 larger, the body has become stouter, and the embryonic caudal is 



