316 PROCEEDINGS OF THE ACADEMY OF 



probably exhibit the ever-changing mycological fauna of the country in a very 

 ditferent light from what it now appears. New species would no doubt be dis- 

 covered, and the boundaries of the old ones more accurately determined. 



Within the week I have obtained 366 /. milium in the locality mentioned, 

 and after considerable search have found only a single shell in the whole field, 

 more than four yards from the spot first designated ; a singular instance of 

 the extreme localization of a species which is quite numerous at that point. 

 Which is respectfully submitted by thy sincere friend, 



E. Micheker. 



Dr. Hayden reported the discovery of a Mastodon tooth in the Post- 

 pliocene drift near Fort Kearney, and another in the same formation 

 in the bluffs opposite St. Louis. 



E. D. Cope pointed out the anomalous relations existing between the tibia 

 and fibula in certain of the Dinosauria, as illustrated by the genus Laelaps. 

 He remarked: The distal extremity of the tibia is transverse, and much com- 

 pressed, and does not exhibit any of the usual appearances of an articular sur- 

 face, neither the reptilian condyle, nor a cotyloid cavity sufficient for an astra- 

 galus of the size necessary for an animal of such bulk. A bone, presenting a 

 broad hour-glass-faced articular surface was discovered with the other remains, 

 and had puzzled the anatomists who had seen it. This piece exhibits, along its 

 whole posterior aspect, two faces, which form a reentrant angle for a fixed arti- 

 culation : this is found to have been applied to the extremity of the tibia, ex- 

 actly, and to have been fixed by strong articular ligaments. The medially con- 

 stricted condyle presenting forwards and a little downwards exhibits so little 

 analogy with the artragalus, as to suggest other interpretations, and, after a 

 careful examination, it seems evidently the distal extremity of the fibula. 

 This element furnishes a small articular surface at the knee, and fitting the 

 tibia by the concavity of its inner face, becomes greatly attenuated at its distal 

 third, where it is, in consequence of an obliquity of its direction, applied to the 

 anterior face of the former bone. It then spreads into a plate extending to the 

 inner margin of the tibia, while the solid shank is continued along the outer 

 margin, and both terminate in the massive condyle which embraces the whole 

 extremity of the tibia, like an epiphysis. 



One other example only of this structure is known in the Vertebrata, of 

 which I only find mention in Cuvier, Ossemens Fossiles x., p. 204, tab. 249, 

 fig. 34-5. This author studied the distal extremity of a tibia with applied fibu- 

 lar condyle, from Honfleur, which he was not able to assign to any known spe- 

 cies or genus, but which he, with usual sagacity, includes in the chapter 

 devoted to Megalosaurus. 



He however regarded the face of the tibia receiving the condyle-bearing 

 bone as the inner, instead of the anterior, stating that the tibia is laterally 

 instead of antero-posteriorly compressed, so anomalous is this structure among 

 vertebrates. He regarded the bone as the astragalus, and did not perceive any 

 connection between its ascending apophysis and a fibula, partly because a 

 fibula with distinct distal articulation was received with the same bones. 



The fibular condyle possesses an articular facet on its exterior extremity, 

 (anterior, Cuvier), probably adapted to a corresponding face of a calcaneum. 

 Its plane is transverse and does not cover the whole extremity, the anterior 

 margin and a knob on the antero-superior part of the extremity projecting 

 beyond it. Exterior to the middle of the upper margin of this piece, and at the 

 internal base of the ascending apophysis, it is perforate, as is the cavity above 

 the condyles of the humerus in the higher apes, and may have received a simi- 

 lar coronoid process of an astragalus. 



As compared with the species examined by Cuvier, this fibular condyle has 

 a less elevated form ; in Cuvier's specimen the ascending apophysis was flatter, 

 broader and directed toward the calcaneal facet instead of from it ; it lacked 



fNov. 



