PKEFACE. 



in the country will thus have the means of accurately identifying 

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

 sent to the National Museum, 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 third Decade gives figures and descriptions in the first 

 plate of the largest species of Seal, the Sea-Leopard, occurring on 

 our coasts. 



The second plate represents another marine mammal, the yellow- 

 sided Dolphin, or Bottle-nose of sailors, occasionally following shoals 

 of fish into Hobson's Bay. 



The third plate shows the characters of three species of danger- 

 ous, poisonous snakes, hitherto confounded under the name of 

 " Brown Snake." One of these is the large deadly " Common 

 Brown Snake ;" of the other two, not before figured or described, 

 one is distinguished by the much smaller scales, in more numerous 

 rows, across the neck and back ; while the third is marked by the 

 great size of the rostral shield covering the anterior part of the 

 head ; all three being equally large and venomous. 



The fourth plate represents the seventeen Victorian species of 

 the beautiful genus Catenicella, which may almost be looked on as 

 characteristic of the Australian seas, from the number of species 

 and abundance of individuals of these exquisite objects for micro- 

 scopic observation occurring in Australasian waters, and the fact 

 that comparatively few are found elsewhere. 



The fifth and sixth plates give illustrations of all the known 

 Victorian species of Membranipora, another genus of the same 

 order, Polyzoa, of minute, beautiful objects, really allied to the 

 Mollusca % but often popularly called Lace- Corals, from their delicate 

 tracery and a mistaken notion of their affinities. The Polyzoa 

 abound in the fossil state in our Tertiary rocks, and the publication 



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