Royal Societi/. 129 



tioned as possessing characters more allied to those of the Pelo- 

 ro.-aurus, or to some unknown terrestrial saurian, than to the Ce- 

 tiosaurus, with which they have been confounded. 



As to the magnitude of the animal to which the humerus belonged, 

 Dr. Mantell, while disclaiming tlie idea of arriving at any certain 

 conclusions from a single bone, states that in a Gavial 18 feet 

 long, the humerus is 1 foot in length; i.e. one-eighteenth part of 

 the length of the animal, from the end of the muzzle to the tip of 

 the tail. According to these admeasurements the Pelorosaurus would 

 be 81 feet long, and its body 20 feet in circumference. But if we 

 assume the length and number of the vertebrae as the scale, we 

 should have a reptile of relatively abbreviated proportions ; even in 

 this case, hoAvever, the original creature would far surpass in mag- 

 nitude the most colossal of reptilian forms. 



In conclusion, Dr. Mantell comments on the probable physical 

 conditions of the countries inhabited by the terrestrial reptiles of the 

 secondary ages of geology. These highly-organized colossal land 

 saurians appear to have occupied the same position in those ancient 

 faunas as the large mammalia in those of modern times. The trees 

 and plants whose remains are associated with the fossil bones, mani- 

 fest, by their close affinity to living species, that the islands or con- 

 tinents on which they grew possessed as pure an atmosphere, as 

 high a temperature, and as unclouded skies as those of our tropical 

 climes. There are therefore no legitimate grounds for the hypo- 

 thesis in which some physiologists have indulged, that during the 

 " Affe of Reptiles " the earth was in the state of a half-finished 

 planet, and its atmosphere too heavy, from an excess of carbon, for 

 the respiration of warm-blooded animals. Such an opinion can only 

 have originated from a partial view of all the phenomena which 

 tiiese problems embrace, for there is as great a discrepancy between 

 the existing faunas of different regions, as in the extinct groups of 

 animals and plants which geological researches have revealed. 



The memoir was illustrated by numerous drawings, and the gi- 

 gantic humerus of the Pelorosaurus and other bones were placed 

 before the Society. 



Feb. 28. — " On the Communications between the Tympanum 

 and Palate in the Crocodilian Reptiles." By Richard Owen, Esq., 

 F.R.S. &c. 



After citing the descriptions by Cuvier, Kaup, Bronn, and De 

 Blainville of the Eustachian tubes and the foramina in the base of 

 the cranium of the recent and extinct Crocodiles, the author gives an 

 account of the nerves, arteries, veins and air-tubes that traverse these 

 different foramina, and thus determines the true position of the ca- 

 rotid foramina and posterior nostrils in the Teleosauri and other 

 fossil Crocodilia, which had been a matter of controversy amongst 

 the authors cited. In the course of these researches the author dis- 

 covered a distinct system of Eustachian canals superadded to the or- 

 dinary lateral Eustachian tubes, which he describes as follows: — 



"From each tympanic cavity two passages arc continued down- 

 wards, one expands and unites with its fellow from the o])positc side 



