67 



the operculae, the slightly obtuse snout, and in the relatively 

 long maxillaries, were more in accord with the charac- 

 teristics of <S. trutta. The shape and number of pyloric 

 caeca were within the overlapping number common to both. 



It is begging the Mdiole question to assume hybridism 

 when the prevailing type is similarly variable, unless we 

 assume also that the ova of one species were artificially 

 impregnated by the semen of the other ]>y mistake prior to 

 dispatch from England. This is conceivable ; but when we 

 consider the names of those who carefully selected the fish 

 in Englf-nd which were stripped, it is not at all probable. 

 Besides, the theory of hybridism is to me extremely unsatis- 

 factory. It assumes that we know the exact measure of the 

 external influence of varying light, food, and the local 

 nature of the medium in which these animals exist. The 

 extraoi'dinary facilities for intercrossing among fishes 

 naturally must also be taken into consideration, together 

 with the fact that the extremes of each type steadily 

 perpetuate themselves in European waters. 



As directly bearing upon this subject, it is noteworthy 

 that already in New Zealand and Tasmania the allied non- 

 migratory species, S.J'ario, var. Ausonii, has developed into 

 distinct types, which are peculiarly characteristic of parti- 

 cular streams. This clearly shows that differences of this 

 kind are not sufficiently fixed to remain unaffected by 

 environment,— that they are in fact racial and subordinate 

 to influences of immediate environment, and not fixed or 

 specific, and remaining constant in spite of such accidental 

 influences. 



BERYCIDiE. 



There are only two known representatives of this family 

 in Tasmanian waters, viz., Beryx arffinh{G.)'. Trachwhthys 

 Madeayi, (Johnston). They are seen on rare occasions, 

 and are consequently of little importance from a utili- 

 tarian point of view. The greater number of genera 

 belonging to the family live at great depths. The genus 

 Beryx is sometimes found at a depth of over 300 fathoms. 



Percid^e. The Perch Family. 

 This family is of considerable importance. It is repre- 

 sented in Tasmanian waters by ten genera and thirteen 

 species. 



