PREFACE. 



for the completion of any one branch. The many good observers 

 in the country will thus have the means of accurately identifying 

 various natural objects, their observations on which, if recorded and 

 sent to the National IMuseum, where the originals of all the figures 

 and descriptions are preserved, will be duly acknowledged, and 

 will materially help in the preparation of the final systematic volume 

 to be published for each class when it approaches completion. 



This sixth Decade gives figures and descriptions in the first 

 plate of a new species of one of those curious Lizards which 

 deceive the popular judgment by assuming the form of Snakes so 

 nearly as to be often mistaken for them. 



The second plate figures another of our rarer poisonous Snakes, 

 too small to be dangerous to man, but of a most striking style of 

 coloring disposed in black and white rings, quite unlike any other 

 Australian land Snake, but like some of the Sea-Snakes in this 

 respect, and in this and other characters reminding us of some 

 types peculiar to South America. 



The third plate shows the characters of our beautiful green and 

 gold Frog, with the various stages of its metamorphosis from the 

 Tadpole aquatic state, by gradually acquiring legs and losing its 

 tail, to the tail-less terrestrial air-breathing form, with four powerful 

 limbs. 



The fourth and fifth plates show the characters of the dissimilar 

 male and female of one of the most gorgeously colored Fishes of 

 our seas, the Aulopus^ especially remarkable for showing the small 

 ray-less adipose dorsal fin near the tail, considered until lately to 

 characterise the Salmonidce^ all of which, whether Trout or Salmon, 

 possess it. 



The sixth plate gives evidence of the identity of Victorian 

 specimens of that extraordinary Fish, the Hammer-headed Shark, 

 with the European type ; and figures for the first time another 

 anomalous Shark, our common Saw-Fish {Prhtiopliorus). 



[4] 



