The President's Address. By Dr. H. Woodward. 140 



tute of feathers. The caudal series of vertebra in some genera (as 

 in Bhamphorhynchus) was greatly elongated, and stiffened with 

 slender ossified fibres. The bones were pneumatic (i.e. filled with 

 air-cavities), the walls of the bones being very thin, and their 

 substance very hard and compact, thus combining strength with 

 lightness. A great American Pterodactyl, Pteranodon, with a head 

 4 ft. long, had its jaws armed with a horny bill and no teeth ; the 

 expanded wings measured about 18 ft. across. The remains of 

 another form, met with in the English Chalk of Kent, had its jaws 

 armed with teeth, and possessed wings of equal expanse. The 

 Dimorphodon, from the Lias of Lyme Regis, had a rather large head, 

 armed with lancet-like teeth, and a long rigid tail, which served 

 — like the same organ in Bhamphorhynchus, from the lithographic 

 stone of Bavaria — as a rudder to steer by, being provided with 

 an expanded membrane near its extremity, like the blade of a 

 canoe-paddle. Many forms, varying greatly in size, some no bigger 

 than a sparrow, others as large as Pteranodon, existed in the Lias, 

 Oolites, Greensand and Chalk, but they have all now disappeared, 

 and left no representatives behind among living beings. 



The Crocodilia make their appearance in the Keuper and Lias 

 and are well represented by long and broad-headed forms in the 

 Secondary and Tertiary periods, but they offer but few points of 

 interest, save to the comparative anatomist, by which to separate 

 them specially from living forms. The Crocodiles belong to Pro- 

 fessor Owen's group the Procoelia, having the vertebrae concave in 

 front ; this includes the long-snouted Garials, as well as the short- 

 headed Alligators and Crocodiles, and various Tertiary forms. 



The Secondary genera belong to Owen's Amphiccelia, in which 

 the vertebra? are concave .at both ends. Belodon, in the Keuper of 

 Stuttgart, and Stagonolejris, in the Trias of Elgin, are among the 

 oldest forms. 



AVES. — Birds are so similar to reptiles in all the most essen- 

 tial features of their organisation, that they may be said to be merely 

 extremely modified and aberrant forms of the reptilian type ; still, 

 the differences which they present are sufficiently great to justify 

 their being placed in a distinct class. Another reason why Birds 

 are placed in an intermediate position between the Eeptilia and 

 Mammals is because, whilst their bony skeleton most closely 

 relates them to the Eeptilia, yet the fact that the chambers of the 

 heart in Birds are completely separated, as in Mammals, the blood 

 in consequence possesses a high temperature — in spite of all the 

 changes of external variations to which they are subjected — the loss 

 of heat being provided against by the clothing of down and 

 feathers, which preserves them from cold, just as the thick coat of 

 hair and wool does in the Mammalia. 



The most ancient type of birds was supposed to be some 

 gigantic forms of struthious birds, such as the Ostrich, Bhea, Emu, 



