122 THE MAMMALS, REPTILES, AND FISHES OF ESSEX. 



considering them too loathsome in appearance. This, how- 

 ever, is not the case in districts where they are more frequent. 

 Yarrell says (British Fishes, vol. ii., p. 451) one was taken in 

 June, 1834, and another in the same month in 1835, as high 

 up the Thames as Sunbury Weir. Day (Fishes of Great 

 Britain, vol. ii., p. 358) gives for their habitat the mouth of the 

 Thames. 



Petromyzon fluviatilis, Linn. LAMPERN OR SILVER LAMPREY. 



Dr. Day (Fishes of Great Britain, vol. ii., p. 360, 361) says 

 they are captured in the Thames, where they abound in 

 quantities. Jenyns says (Brit. Vert. Animals, p. 521) they 

 are common in many of our rivers, especially in the Thames. 

 The same remark is made by Yarrell (British Fishes, vol. ii., 

 p. 454). Lieutenant Croft mentions them (Trans. Herts. 

 Nat. Hist. Soc., vol. ii., p. 15) as found in the Lea. 



They probably occur in all Essex rivers, but, as they are 

 never fished for, I have not had the opportunity of seeing an 

 example. 



Petromyzon branchialis, Linn. PLANER'S LAMPREY. 

 MUD LAMPREY (immature form). 



According to my experience, this Lamprey is rare in Essex 

 streams. I have, however, taken specimens at Lexden, in the 

 Colne, and also in the Roman river, a feeder of the Colne. 



