GEOLOGICAL SOCIETY. 



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of the Plesiosaurus, in which respect these portions of 

 the two fossils closely resemble each other ; they are also 

 similar in the form of the planes of the articulating surfaces 

 of the bodies of the vertebras. But our fossil differs to- 

 tally from the same portion of the Plesiosaurus in its 

 proportions, the vertebras of the latter being broader 

 than long. All the superior apophyses of the Plesio- 

 saurus are attached by suture to their bodies, but there 

 are no marks of such a structure in our fossil. 



Judging from relative proportions, the Megalosaurus 

 did not attain to more than thirty or forty feet in 

 length ; the Iguanodon of Mr. Man tell did not exceed 

 sixty feet ; but the individual now indicated could not 

 have been less than from eighty to a hundred feet. 

 According to the statement of Judge Bry, to whom the 

 society is indebted for the specimens, there were four 

 hundred feet in extent, nearly in a curvilinear direc- 

 tion, marked by these fossils in the soil, which we must 

 presume included the remains of several individuals. 

 If future discoveries of remaining portions of this ske- 

 leton, should confirm the indications above pointed out, 

 we may suppose the genus to which it belonged will 

 take the name, not inappropriately, of Basilosaurus. 



Locality, Banks of the Washita, Louisiana. 



Place in the Geological series. — Atlantic tertiary. 

 The piece of 66 sea-marl" which accompanied the spe- 

 cimen, is a conglomerate mass of small marine shells, 

 principally of an extinct species of Corbula, similar to 

 those observed in the same formation in Alabama. Most 

 of these shells are comminuted ; a few, however, re- 



