552 MULLER ON THE STRUCTURE OF THE GANOIDS, 
distinctly formed by the union of the ribs themselves. In the 
osseous fishes it is quite different; in them they always arise, 
without exception, from the union of the lower apophyses of the 
vertebral body, i. e. of the lower vertebral pieces of the foetus; 
and in a great many osseous fishes the ribs are also attached to 
the lower spines at the extremity of the abdomen. This differ- 
ence between the Gonoidei holostet and the osseous fishes is one 
of the most important osteological distinctions in the division 
of the Vertebrata. It is very desirable therefore that we should 
become acquainted with the feetal state of the vertebral column 
in these Ganoids. In the Sturgeons the lower spine arises as 
usual only from the lower vertebral pieces which cover the whole 
length of the chord. 
Dr, C. Vogt has translated my first treatise on the Structure 
of the Ganoids and the Natural Arrangement of Fishes into 
French, in the Annales des Sciences Naturelles, 1845, July, and 
has appended some observations to it; among them there is one 
which contains a very important fact. In examining the Amia 
calva of the Paris Museum as to the valves and the muscular 
coat of the arterial trunk, which I instituted as characters of the 
Ganoids, Vogt has discovered in it a new Ganoid of the present 
creation. For he found in this freshwater fish from Carolina, 
which Cuvier placed (together with Polypterus and Lepisosteus) 
among the Clupeide, and which I left there, two oblique rows 
of valves in the arterial trunk, and in each row five or six valves ; 
moreover, the arterial trunk, as in other Ganoids, was covered 
externally by a well-defined layer of muscular substance. Ac- 
cording to the same observer, Amia has a screw-like spiral valve 
in the intestine, which makes several turns, without however 
reaching the upper part of the intestine, and which, as in Lepis- 
osteus, is confined to that part only of the intestine anterior to 
the large intestine. Notwithstanding this anatomical resem- 
blance to Polypterus and Lepisosteus, the scales of Amia have 
not the slightest similarity with the former Ganoids; and we 
thus again see how little the scales can be trusted. ‘The scales 
of Amia are by no means osseous plates, they are flexible and 
rounded. Among those fossil fishes which M. Agassiz enume- 
rated as Ganoids, we find similar scales in Megalurus and Lep- 
) tolepis, and this is another reason why these two genera, re- 
specting which I have not as yet arrived at any conclusion, from 
want of positive characters, may possibly be Ganoids. Like 
