BY R. M. JOHNSTON, F.L.S. 45 



A study of the analytical table given reveals the fact that 

 with the exception of one, or perhaps two, out of the 32 

 points, all the characters not only vary with each individual 

 of the same species, hut the range of this individual 

 variability covers or overlaps the wholeof the different species 

 in English and Tasnianiau types. The characters which 

 alone serve to distinguish the English S. salar are — the trans- 

 verse series of scales between lateral lino and root of adipose 

 fin, and the relative length of maxillary in adult specimens. 



The specially distinguishing characteristics of Tasmaniau 

 fishes as compared with their British and Irish pi'ogenitors 

 are common to the migratory and fresh-water forms, viz. : — 



1. The prevailing greater relative depth and girth of the 



body. 



2. The prevailing higher number of pyloric cseca* 



ranging as high as 56 in the brown trout form ; the 

 range of the local analogue of -S*. salar reaches as 

 high as 72. 



3. The prevailing greater relative length and depth of 



the dorsal and anal fins. 



4. The prevailing greater relative distance of the dorsal 



fin from the occiput. 



5. With the exception of the small silvery form of sea 



trout, the prevailing larger size of the adipose fin, 



with about six well-marked rows of rudimentary 



scales ascending upwards some distance from its 



base ; the only distinguishing test between some 



of the large brown trout of the Great Lake and the 



migratory fish entering the sea is one of colour and 



ornamentation. No two specimens of the Great 



Lake fish agree in size, form, and number of the 



spots, nor in the general colour of the body ; some 



having a deep brownish shade, while others are of a 



bright silvery colour, without a red spot or shade of 



brown. Between these there is every possible 



gradation. Every river has the effect of producing 



some more or less marked local characteristics. 



Where the brown trout inhabit streams near to the sea 



they enter the salt water freely, and soon assume a bright and 



silvery appearance, although in mosc cases the tinge of the 



golden shade and their greater size readily distinguish these 



from the smaller S. trutta, which seems to "linger in the salt 



water for a longer period (usually from July to November and 



December), and ranges farther towards the open seas. 



* This great increase ia the number of pyloric cjcca has also beeu noted 

 Bpecially in New Zealand by Jlr. Arthur. 



