the Salmon, Herring, and Vendace. 507 



the lake (the vendace excepted), are readily taken with the 

 usual baits. 



1 have subjoined a drawing of the food, as seen under the ex- 

 cellent microscopes of Dr GREVILLE, and Mr GRAHAM DALYELL, 

 to whom I owe my best thanks, not only for the interest they 

 manifested in these inquiries, but likewise for the very great 

 trouble they took in verifying my observations, and in giving me 

 the command of their microscopes at all times. The animal, as 

 examined in the various specimens placed under the microscope, 

 and represented in the accompanying engraving, is either imper- 

 fect, or has not been described by authors. Its apparent imper- 

 fection may arise from its having been acted on by the gastric 

 juices of the fish. It seems to approach nearest the Lynceus 

 lamellatus and Trigonattus of MULLER. A few have dried up 

 on the glass, upon which they were examined, and can still be 

 well seen with the aid of a good microscope *. 



The discovery of the food of the vendace or corregonus of 

 Lochmaben, led immediately to that of the herring : it became 

 impossible to overlook the strong analogy subsisting between the 

 species ; and although the one was marine and the other lacus- 

 trine, we know their differences as to habitation to be but trifling 

 in the great economy of nature. But even here some difficulties 

 presented themselves, although the key to the discovery was in 

 my hands ; the extremely minute microscopic shell-fish or en- 

 tomostraca, which was immediately discovered to be the food of 

 the herring, were found to be more broke down than in the case 

 of the vendace, and the food could not in any case be got for ex- 



* It is mentioned in Captain FRANKLIN'S Journey to the Polar Sea, that the 

 stomach of the Corregonus Signifer or Back's Grayling " is generally filled with 

 gravel or black earth." This black earth, I presume, may be the remains of the 

 testaceous entomostraca or other microscopic shell-fish, on which this kind of Corre- 

 gonus probably subsists. 



VOL. XII. PART II. 3 T 



