52 Cat-Jishes oftJie River Ohio. 



rated anteriorly, no visible lateral line, anal fin with 15 rays, 

 tail elliptic. 



A small species which lives in muddy bottoms, and is always 

 covered with mud. General tinge a rufous brown, belly gray, 

 barbs black, spinous dorsal ray short, smooth, half-concealed 

 in the membrane ; spinous ray of the pectoral fins large, broad, 

 flat, and serrated outside. D. 1 and 6. P. 1 and 9. Abd. 8. 

 A. 15. C. 20. 



All the silures of the Ohio are probably common to its tri- 

 butary streams, and even to the Missouri and Mississippi. 

 They are voracious fishes, which live on smaller fishes ; they 

 are easily caught with the hook, and are very good to eat, par- 

 ticularly the large species. 



There are yet many species in the western rivers of the United 

 States ; they may be easily distinguished by attending carefully 

 to the colours, length of the jaws and barbs, shape of the tail, 

 eyes and lateral line, number of rays, §c., which all afford good 

 specific distinctions. 



Transylvania University, ' C. R. RAFINESQUE. 



\%\. October, 1819. 



Aet. V. On Fluidity ; and an Hypothesis concerning the 

 Structure of the Earth. 

 It has been affirmed by Lavoisier*, that, without atmo- 

 spheric pressure, there would be no permanent liquid ; and 

 bodies would be seen in the liquid state, only at the very instant 

 of melting, for they would pass instantaneously from the state 

 of solid aggregation to that of aeriform elasticity. With- 

 out atmospheric pressure too, there would be no proper aeri- 

 form fluids ; because, the moment the force of attraction is 

 overcome by the repulsive power of caloric, the particles of 

 bodies would separate themselves indefinitely ; having nothing 

 to limit their expansion ; unless their own gravity might 

 eoUeci them together, so as to form an atmosphere. 



• Elements of Chemishy. 



