102 



EXPLANATION OF KEY TO ORDERS AND 

 FAMILIES. 



The Key is arranged according to the branched or binary system 

 of the French Naturalist, Lamarc. This plan has been adopted? 

 with great success, by the late Rev. W. W. Spicer, M.A., in his 

 '* Handbook of the Plants of Tasmania." 



The method consists of a series of pairs of characteristic 

 descriptions so arranged that the student, by commencing with 

 the first pair, is led, by the acceptance always of one out of two 

 propositions, to the next pair by the aid of numbers, which cor- 

 respond with consecutive index numbers to the several pairs of 

 the descriptive propositions. This course is pursued until the 

 student is finally brought to the Family number, which, for 

 distinction, is printed in Roman characters. By turning to the 

 corresponding number in Classified Catalogue, the student may 

 easily find the particular genus and species by means of the 

 symbolic and abbreviated characters given after the name of each 

 species under the family. 



For example : if the fish under examination be the Holart 

 Trumpeter^ the student would find, under Primary Division, 

 that it agreed with the first proposition of No. 1, which leads to 

 pair No. 4. The examination of No. 4 would lead to the 

 acceptance of the second proposition, leading to pair No. 8. It, 

 in turn, by following a similar course, would lead to the adoption 

 of the following, in sequence ; viz. — No. 10, the first leading to 

 No. 11 ; No. 11, the first leading to No. 12 ; No. 12, the second 

 leading to No. 15 ; No. 15, the/r5^ leading to No. 16 ; No. 16, 

 the first leading to No. 17 ; No. 17, the second leading to No. 18 ; 

 No. 18, the^?-s^ leading to No. 19 ; No. 19, the 5ecw2c? terminating 

 in CiRRHiTiDiE — VI. If we now turn to that family in the 

 Classified Catalogue, we would find that the number of spinous and 

 soft rays in Dorsal, Anal, and Pectoral (viz.— D. 17 : 1-36-38. 

 A. 3-28 - 30. P. 9-8 - 9.) would finally lead to the true name 

 of species, viz., Zatiis hecateia, Rich. — The Trumpeter. 



A little practice will enable any person of ordinary intelligence 

 to determine any of the known Tasmanian fishes by this method. 



