[87] THE OSTEOLOGY OF AMIA CALVA. 833 



tail of Aniia has been figured and described by Franque. Kolliker, and 

 Huxley." ^s 



Kolliker's paper is known to me only through the quotations by 

 Dum^ril. Franque represents only the osseous portions of the skeleton. 

 Huxley gives both form and structure, but not, as it seems to me, quite 

 accurately. Neither of these authors mentions the young Amia, or inti- 

 mates that the form or structure of the tail may vary with age. In 

 discussing the external form this author further remarks that " Dumeril 

 says that the tail of Amia, as to its external appearance, differs in no 

 way from that of the ordinary osseous fishes. Its heterocercy, however 

 decided, is well manifested only by the skeleton." Huxley does not 

 allude to the form, but his figure does not very distinctly indicate any 

 difference between the tail of Amia and that, for instance, of some Silu- 

 roids, where the whole is rounded, and the greatest length is midway 

 between the dorsal and ventral borders." ' 



And, continuing, in the same article he sums up the results of his val- 

 uable observations, and says : " I have examined many examples of 

 Amia, young and adult, and all manifested the following features : 



" 1. The greatest length of the tail is considerably above the middle 

 of its height. 



" 2. The change from the nearly horizontal dorsal and ventral borders 

 to the curved posterior border occurs farther forward upon the ventral 

 side. These features render the ventral slope both longer and more 

 gradual than the dorsal. 



" 3. When the tail is fully expanded, as while the fish is swimming, 

 the dorsal and ventral slopes meet, so as to form a gentle curve, and 

 not an obtuse point, as in Huxley's figure. This is well shown in (Fig. 3 

 representing) the tail of a young example in the condition assumed at 

 death. 



" The tail of Lepidosteus presents the same general features, with some 

 specific variation. Hence, with both these ganoid genera the external 

 form of the tail is decidedly, though not very obviously, unequal." 



My interest was first awakened in the structure of Amia more than 

 ten years ago, at which time I was permitted to attend Dr. Wilder's 

 lectures at Cornell University, where dissections upon Amia calva al- 

 ways held a prominent place. In those days, however, if I remember 

 correctly, Dr. Wilder had made but few, if any, dissections of the 

 young of Amia, so it affords me additional pleasure and a peculiar 

 satisfaction to further quote from his paper in the Proceedings his 

 remarks upon the structure of this part of the mudfish's anatomy, 

 supplemented, as it now has been, by studies in that direction. Of it 

 he says that " the terminal caudal vertebrae form an upward curve, 



^ I have, for obvious reasons, referred to elsewhere in this article, omitted Dr. 

 Wilder's number references to his bibliographical table at the end of the above paper 

 in the Proceedings; as well as the references in his text to the figures of his ia- 

 structive plate. 



H. Mis. 67 53 



