180 



PROCEEDINGS OF THE ACADEMY OF 



molar differs remarkably from that of Jtl. Jeffersonii and M. dissimilis, as is also 

 the case compared with that of Lestodon armatus and L. mi/loides of Buenos 

 Ayres. lu transverse section it is reniform or crescentic with blunt poles, and 

 the biting extremity appears to have been worn off in the same manner as the 

 incisors of a Rodent, to which, indeed, the jaw appears first to have been sup- 

 posed to belong. The species may be named Megalonyx rodens, or, if the 

 peculiarities of the caniniform molar be regarded generically distinct from 

 those of Megalonyx and Leslodon, it may be named Megalocnus rodens. 



Emys Sombrerensis, n. s. 



The bones of extinct species of turtle are not unfrequently found in the so- 

 called Sombrero guano, Sombrerite or Ossite, a material rich in phosphate of 

 lime, largely mined in the island of Sombrero, W. I., and used in the prepara- 

 tion of a fertilizer for agricultural purposes. In a mass of this material pre- 

 sented to the museum of the Academy (see Proc. 1859, 111), the posterior part 

 of the plastron of a species of Emys, or perhaps Testudo, is perceived, for which 

 the above name is proposed. The specimen consists of both xiphisternals and 

 the greater portion of both hyposternals, articulated in natural juxtaposition. 

 Other fragments of the plastron and carapace, together with a portion of a 

 thigh bone, are also contained in the mass. The specimen indicates the ster- 

 num to have approximated a foot in length ; and the breadth at the lateral 

 sutures of the hyposternals has been about 7^ inches. The under surface of 

 the sternum is flat and smooth ; and laterally it curves but slightly upward. 

 The posterior sternal notch is two-thirds as deep as the width, and almost 

 forms an equilateral triangle. The postero-lateral border from the inguinal 

 notch to the rounded triangular ends of the xiphisternals, is bow-like, or pre- 

 sents two concavities with an intervening convexity. The caudal scutes are 

 small, reaching slightly beyond the bottom of the sternal notch. The femoral 

 scutes are on a level with the inguinal notches. Estimated length of hypo- 

 sternals in the median suture 35 lines ; breadth 45 lines. Length of xiphi- 

 sternals in median suture 17 lines; greatest length about middle 25 lines; 

 breadth along anterior suture 28 lines. Length of caudal scutes internally 13 

 lines ; externally 10 lines. Length of femoral scute internally 25 lines. The 

 bones present about the ordinary proportion of thickness observed in eniydes. 



July nil, 1868. 



Dr. Bridges in the Chair. 



Twenty-one members present. 



The following papers were presented for publication : 

 "Notice of some remains of Horses." By Joseph Leidy, M.D. 

 " Notice of some extinct Cetaceans." By Joseph Leidy, M.D. 

 " Mitchella repens ; a Dioecious plant." By Thomas Meehan. 



July 14ih. 

 The President, Dr. Hays, in the Chair. 

 Nineteen members present. 



The following papers were presented for publication : 

 " Second contribution to the history of the Vertebrata of the Mi- 

 ocene period of the United States." By Edw. D. Cope. 

 " Remarks on Conosaurus." By Joseph Leidy, M.D. 

 " Remarks on a jaw fragment of Megalosaurus." Jos. Leidy, M.D. 



[July, 



