430 Correspondence — Mr. A. R. Hunt. 



definite shapes and proportions of some of the great and long- 

 unknown reptilian masters of the world, whether dignified in their 

 monstrous bulli and unused power, as Herbivores, or domineering 

 as the Carnivorous tyrants of their day" (Geol, Mag. 1869, p. 566). 



Jlypsilophodon, Compsognathus, and Sallopus are the smallest 

 — the first about four feet long, and the last " about the size of a 

 fowl," and probably light enough to hop about. The larger forms, 

 such as Ignanodon in Europe, and Claosaurus and others in America, 

 reached about thirty feet in length and fifteen in erect height. 

 These animals, (like Crocodiles) adapted for both swimming and 

 walking, have left their tracks on former mud-flats and sand-banks, 

 as in Sussex and Connecticut. In the latter district they are mingled 

 with possible bird-tracks and probable labyrinthodont footprints. 



Beginning with the Trias, they ended their career in the early 

 part of the Cretaceous period ; and they brought with them certain 

 structural peculiarities, which became more developed and specialized 

 in Birds. The Pterodadyle (flying reptile) and ArchcBOpteryx 

 (reptilian bird) present other such evidences of progressive stages 

 among life-forms. 



The "Ancient Birds" have Chap. viii. to themselves, bringing 

 the reader through the Cretaceous period, with its toothed birds, to 

 a few centuries and less ago when the Moa, Dodo, Solitaire, and 

 Great Auk have succumbed to destructive Man. 



Chapter ix. begins a new era of the history of the " Creatures of 

 Other Days," with animals of the Tapir and Elephant types ; those 

 belonging to the Horse, Whale, and Wombat occupy Chapters 

 X. and xi. ; and some extinct South-American creatures, and the 

 Californian Ox, end the series in Chapter xii. 



The most advanced and highest Mammals are doubtlessly shown 

 in Plates i. and xii., though the latter is placed in the Dinosaur 

 chapter ; for Eichard Owen, Huxley, Marsh, Cope, von Zittel, and 

 Gaudry, are here pourtrayed as representative palasontologists. The 

 other numerous illustrations have also been carefully prepared, and 

 in many cases are artistically good. 



Certainly verbal errors (by author or printer) are not absent ; and 

 there are obscurely elliptical phrases, such as " the genus must have 

 been as large as an ostricht" (p. 161). The author's own "kind 

 friends" will probably have drawn his attention to some such 

 weaknesses, and to points on which differences of opinion are held. 

 We need only say that the book is clearly and pleasantly written ; 

 it is full of desirable information well considered and conveniently 

 arranged. T. E. J. 



coi^K-ESiE'oifrnDZBn^oiE]. 



DYNAMICAL METAMORPHISM. 



Sib, — In connection with my friend Mr. Harker's remarks on 



experimental dynamic metamorphism, some of your readers may 



be interested to try for themselves one of the simplest cases. 



Apparatus — a teaspoon, a lamp, a sheet of paper, and a few crystals 



