AND ON THE CLASSIFICATION OF FISH. 507 
When I first examined the Polypterus on this point, I was 
much astonished on finding that this so-called osseous fish dif- 
fered from all other osseous fishes in its valves, and that it 
agreed in that respect with the higher cartilaginous fishes, the 
Sturgeons, the Rays, Sharks and Chimera, and far exceeds them 
in the number of valves. The Polypterus possesses no valve at 
the origin of its exceedingly long muscular bulb; but within it 
there are three longitudinal rows of valves, in each of which there 
are nine segments, which are connected by filaments, as in the 
Sturgeons and Plagiostomi. The uppermost are as usual the 
largest. Between the three complete rows of large valves there 
are three other longitudinal rows, the valves of which are less 
developed both in size and number, so that the perfect longitu- 
dinal rows alternate with the imperfect. Thus there are alto- 
gether six longitudinal rows. If the imperfect rows were as 
complete as the perfect ones, Polypterus bichir would have fifty- 
four valves in the muscular arterial trunk ; there are in fact only 
forty-five present. 
It was to be expected that this peculiarity would also be found 
in Lepisosteus, of which at first I had no specimen. I lately 
examined it in the Jardin des Plantes at Paris. Lepisosteus 
osseus has five equally developed rows of valves in the arterial 
trunk, in each longitudinal row eight perfect sacculated valves, 
connected by filaments. Those of the uppermost oblique rows 
are longer. The rows appear like the cups of a well-wheel or a 
machine for removing mud. No cartilaginous fish possesses so 
many valves as the Ganoidei spoken of. In the Sturgeon there are 
twelve only ; and in the Rays and Sharks, where their number 
reaches its maximum, there are not more than fifteen present, as 
in Raia, Myliobatis, Pteroplatea, Scymnus and Squatina. 
We have now discovered a character which removes the 
Sclerodermi, Gymnodontes, Siluroidei, Goniodontes and Lophio- 
branchii, distinctly from the Ganoidei, and refers them to the 
true vertebrated osseous fishes. According to my observations, 
all these fishes agree with the other osseous fishes in their or- 
ganization ; especially, as far as to the present point, they re- 
semble all true osseous fishes, in the fundamental peculiarity of 
the arterial trunk being furnished with two valves at its origin. 
In the Sclerodermi I have examined the genera Balistes and 
Ostracion ; in the Gymnodontes the genus Te¢rodon ; in the Si- 
luroidei the genus Calophysus, M. T.; in the Goniodontes the 
genera Hypostoma and Loricaria; in the Lophobranchii the 
