On the Iiuvj»! development of Amia calva. 669 



earliest stages tlicy would give üo tlelinite cliic as to their ancient 

 form or relationships. Aiul in like maiiner in the trunk regiou niight 

 the sanie principle be apjjlicd; thus at a defiuite point on tlio trunk 

 wall could be produced tiu structures at once large aud porfected ^) 

 wliose eutire modc of growtli should give little evidence of re- 

 capitulation. 



C i 1 i a t i n. 



The ciliation of the body of the Amphibians, as recently de- 

 scribed by Assheton 2), does not appear to find a parallel among 

 larval Ganoids. The present writer has been iinable to find in Amia 

 any tracts of ciliated epithelium other than those which form the 

 mucous cauals. The present observations, however, were made en- 

 tirely upon preserved material, but tbis it may be noted was so 

 favorably preserved that the cilia of the sensory canal regions and of 

 the gut were clearly distinguished. 



IT. Conclusions. 



From palaeontological studies there can be little doubt that a 

 series of transitional forms, closely Araioid, included in the families 

 Eugnathidae, Amiidae, PacJiycormidae , PhoUdophoridae and Lepto- 

 lepidae, provide the actual stepping stones from the Ganoids to the 

 Clupeoid Teleosts. And as this genetic relationship of the Teleosts 

 is now Coming to be widely recognized it becomes less important to 

 harmonize differences between the later and the older groups on the 

 side of their embryonic and larval development. In the ontogeny of 

 Amia, however, can now be fouud the final evidence of this genetic 

 kinship — to serve both to confirm the palaeontological results, and 

 to cause these to be accepted unhesitatingly by the embryologist. In 

 the early stages of development the nearnesses of Amia to the 

 Teleosts have already been shown, and in the present paper the larval 

 stages of these forms have been found to possess many striking simi- 

 larities, as in the development of the hinder digestive tract, post-anal 

 gut, unformed neurenteric canal, hinder excretory ducts, liver and 

 yolk, pronephros, brain, neuromeres, hypophysis. 



But the especially suggestive feature which a study of the larvae 

 of Amia has brought out is the matter of precocious development. 

 W e find, for example, that the organogeny of Amia progresses more 



1) As in Ceratodus, as figured by Semon. 



2) in: Quart. J. Micr. Sc, V. 38, 1896, Part 4, p. 465—484. 



