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.