INTRODUCTION. 17 



are usually provided with- tendril-like filaments for their 

 attachment to other objects. Many of my readers are, 

 no doubt, familiar with those wonderful objects, the eggs 

 of the Port Jackson Sharks. These are relatively enor- 

 mous when compared with the size of the parent itself 

 and the beautiful concentric spiral arrangement of the 

 outer covering, must always inspire a feeling of admira- 

 tion in the beholder. 



The Classification of Fishes: For purposes of 

 reference, fishes which belong to a class called by Natu- 

 ralists, Pisces are separated into two main sub-classes 

 known as the Elasmobranchii and the Teleostomi; with 

 a third and smaller one called Dipneusti or Dipnoi; the 

 latter including the remarkable Lung-fishes. These sub- 

 classes are again divided into orders, sub-orders, and 

 many families; the families themselves being split up into 

 genera and species; the genus and species forming what 

 is called the scientific name. For instance, in the case of 

 the Nannygai, the scientific name is Beryx af finis; the 

 former being the genus, and the latter the species. Fishes 

 having certain slight affinities with one another, are 

 grouped together under the main divisions, while those 

 showing a greater and still greater natural relationship 

 to one another, are placed in the more and more restricted 

 groups. Generally speaking, this is the plan followed by 

 all Zoologists and Botanists in classifying animals and 

 plants ; the idea being to make the system of classification 

 as natural as possible, and as far as possible obviating the 

 formation of artificial divisions. Unfortunately, however 

 ardently a person may desire it, the latter cannot always 

 be carried out in practice ; in many cases, through our 

 imperfect knowledge of the groups that we are dealing 

 with. This being so, scientific nomenclature is likely to, 

 and does, change; in accordance with the state of our 

 knowledge. In the accompanying table, I have shown the 

 system of classification followed in this little work. This 

 is (with slight alteration) the arrangement followed by 

 the authors dealing with the fishes in Volume VII. of the 

 Cambridge Natural History (1904). 



Incidentally, I might here mention, that a great many 



