[57] THE OSTEOLOGY OF AMIA CALVA. 803 



" In continuing in its cranial structure the anatomical facts expressed 

 in paragraphs I-IX inclusive, Amia differs from all other living Gan- 

 oidei, and exhibits distinct and decided affinities to such generalized 

 types of physostomus Teleostei as the Siluroidei, Cyprinoidei, &c. On 

 the other hand, in common with all other Ganoids, Amia possesses sev- 

 eral points of resemblance with larval and adult forms of Amphibia, 

 especially as regards the structure to which attention has been directed 

 in i^aragraphs IV, X, and XI." 



"Moreover, in the angulation of the mandibular arch, caused by the 

 forward growth of its metapterygoid element, we have a repetition of 

 an arrangement characteristic of the adult frog, and of certain Sela- 

 chians, Notidanus. But notwithstandiug these evidences of widespread 

 affinity it is evident that if, in addition to the above-mentioued facts, 

 we credit Amia with the possession of cycloid scales, uon-lobate fins, a 

 nearly homocercal tail, and note the absence of spiracles, the Teleostean 

 affinities predominate ; and it may be asked whether, despite certain 

 peculiarities in structure of its generative organs and bulbous arteriosus, 

 the gap between the ganoid Amia and the physostomus Teleostei is not 

 less than need be expressed by ordinal distinction. It may be that just 

 as Polyi^terus and its near ally of the same family are the sole surviv- 

 ing examples of the otherwise long extinct order of Crossopterygian 

 Ganoids, so the Amiidse are the sole survivors of those widely- general- 

 ized Ganoidei out of which more specialized Teleostei were directly 

 evolved." 



Now, if it were my intention to carry the comparative studies of the 

 skeleton of Amia further than Dr. Sagemehl has in Part I, I would enter 

 the tempting fields offered by the minute examinations that coidd be 

 made of other American Ganoids and compare them in every particular 

 with our subject. Then comparisons made with the complete skeletons 

 of Mops and Megalops would be particularly interesting, and on some 

 future occasions these may be treated as I have endeavored to treat 

 Amia in this paper. But to undertake such comparisons here would 

 lead me far beyond the intention and scope of my original plan. 



It does, however, fall within the limits of this plan to present here a 

 concise review of the skull and other i^arts of the skeleton of a well- 

 specialized Teleostean, more particularly the skull. Such a review, it 

 is hoped, with its illustrations and figures, will be valuable, from a com- 

 parative point of view, taken in the present connection, as well as form- 

 ing a groundwork for future studies or the observations of others enter- 

 ing upon the study of the anatomy of fishes for the first time. 



Of a Teleostean sJcull. — For my review of this part of the skeleton of 

 a Teleost and for references to such other parts of the osseous system as 

 I propose to enter upon, I have chosen a specimen of Micropterus sal- 

 moides. This was done because the large-mouthed black bass is a fish 

 of pretty general distribution in the United States, and consequently 



