FOSSIL SQUALID^ OF THE UNITED STATES. 203 



8. O. DESORii, Gibhes. Figs. 169 to 171. — Professor Agassiz described under this 

 name specimens, which subsequent experience induces him to consider identical with 

 Lamna cuspidata, with which he had noticed a resemblance. 



I take pleasure in restoring the name of the distinguished M. Desor, the friend and 

 co-labourer of Agassiz, in this department of science, to a fine species in my Cabinet • 



It is very massive, thicker than any other of this genu.s, in this respect resembling 

 Oz. crassa, but not so broad. Viewed en profil, the form is similar to Lamna Hopei, 

 much curved inwardly, except near the apex, which is flat. The edges are cutting 

 in their whole extent, the base of the enamel arched, and nearly equal on both faces, 

 the root very thick compact and heavy. I have several specimens from the Miocene, 

 and others from the Eocene of South Carolina. 



9. O. wiLSONii, Gibhes. — Figs. 171, 172,173. — This resembles somewhat O.r.Aa^^a/w^ 

 but is convex on the outer face, the root also is thicker and more largely developed. 

 The cone is straight, equilateral, and very acute, slightly curved near the base. The 

 root is very convex on the inner and concave on the outer face, the branches 

 irregular. The enamel is arched on the inner face, and waved on the outer. 



I believe this species distinct from other American varieties, and propose for it the 

 name of Dr. Thomas B. Wilson, the patron of the Academy. 



When I commenced my investigation of the Fossil Sqiialidce, it was my purpose 

 to attempt a microscopic arrangement. Professor Agassiz having informed me of his 

 intention to undertake such researches, both of the recent and fossil genera, I prefer 

 to yield to his experience and opportunities what I could but partially and 

 imperfectly effect. In the present state of our knowledge, it is convenient to make a 

 pro tempore division of the Squalidcs, into those having crenated teeth, and those 

 which are smooth, as follows : 



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