Dr. Knox on the Food of certain Gregarious Fishes. 57 



them, from the fragments hitherto collected, with those of the pre- 

 sent flora. The results hitherto obtained only entitle us to say, — 

 Palms make no exception to the rule generally received, that the 

 laws governing the vegetable kingdom were the same in all periods 

 of our earth's history when plants existed ; and that the species of 

 Palms have a very local geological, as they have a very local geo- 

 graphical distribution." 



December 19. — Thomas Bell, Esq., President, in the Chair. 



Read a Memoir " On the Food of certain Gregarious Fishes." By 

 Robert Knox, Esq., M.D. 



Dr. Knox's inquiries were commenced about thirty years ago, and 

 the results then arrived at were communicated to the Royal Society 

 of Edinburgh, in whose 'Transactions' a notice of the paper was 

 published. Since that period the observations have been repeated 

 on many occasions, and the author does not find it necessary to alter 

 or modify the statements which he originally made. His attention 

 was first directed to the fact, that in the stomachs of Salmon, fresh 

 from the recesses of the ocean, nothing is ever found except a small 

 quantity of a peculiar reddish substance, unlike anything known to 

 possess life. Practical fishermen agreed in the opinion, that the food 

 of the Salmon, while resident in the ocean, was altogether unknown ; 

 neither could they give any satisfactory account of that of the Herring. 

 Having learned accidentally, that in a lake or lakes near Lochmaben 

 there existed in great abundance a small fish (the Vendace) which 

 could not be tempted by any bait, and whose food was entirely un- 

 known, he determined to visit Lochmaben, and make this fish, so 

 easily procured, the subject of his researches. Dozens of Vendace 

 were taken in nets, and immediately opened ; and their stomachs 

 were found crammed with thousands of Entomostraca, which were 

 immediately recognized on placing a portion of the contents of the 

 stomach under a strong lens. The species first discovered belonged 

 to the genus Lynceus ; but several other genera were subsequently 

 observed; and in winter, that is to say, on the 14th of December 

 1832, several species of Cyclops, Miill., most abounded. The notion 

 that the Vendace dies immediately on being taken out of the water, 

 Dr. Knox found to be quite erroneous. It is by no means a very 

 delicate fish, and could easily be transplanted to other lakes ; but its 

 good qualities have been much exaggerated. 



The author next enters into some detail on the distinctive charac- 

 ters of a number of Vendace, both males and females, caught partly 

 in the Castle Loch and partly in the Mill Loch, and which were 

 carefully examined by his brother with a view to their supposed 

 specific distinction. He treats as a delusion the idea that the males 

 live apart from the females in deeper water, for a single draw of 

 the net in the Castle Loch, in the presence of Mr. Murray and 

 himself, was found to produce nine females and six males, although 

 of forty taken in the Mill Loch at one time only two were males. 



