Petromyzon. 
FISHES. CHONDROPT. 
163 
CHONDKOPTEKYGIOUS FISHES. 
Gen. I. PETROMYZON. Lamprey. — Maxillary ring, 
armed with teeth. Mouth ovate, longitudinal. 
\ 1. P, marinus. Sea-Lamprey. — Marbled with black, brown, 
and yellow. The second dorsal and caudal tins disjoined. 
Lampetra, Merr. Pin. 188 — L. Rondeletii, Will. Ich. 105. — P. mar. Linn, 
Syst. i. 394. Penn. Brit. Zool. iii. 76. — Lamprey Eel ; IF, Llysowen 
bendol. — In the sea and large rivers frequent. 
Length between two and three feet. Body of nearly equal thickness to the 
first dorsal-fin, when it decreases suddenly to the tail. Head rounded anteal- 
ly, with a slight constriction over the eyes, and rather less than the body. 
The first dorsal-fin semicircular in its outline. The second rises gradually a 
little behind the former ; and, after reaching its greatest breadth, somewhat 
suddenly, it gradually diminishes towards the tail. The tail is rounded ; the 
rays at the end are short ; and, on the under side, from opposite the second 
dorsal-fin, there is a ridge continued to the anus. Eyes lateral, in a small 
cavity in front of the gill-openings. Nostril, or short tube, situate in the 
middle, on the hind head. The sucker is a narrow border, surrounding the 
lips, consisting of an outer row of conical papillae, and several inner rows of 
short, compressed, digitated, fringed processes. Secondary or moveable teeth, 
short, conical, or bifid, disposed in diverging and concentric rows. Primary 
teeth two ; the one above, consisting of two contiguous processes ; the one be- 
low larger, lunate, with seven conical processes. Tongue small, Avith several 
rows of small teeth. Gullet short ; the alimentary canal simple. The gill- 
openings are seven on each side, ovate, transverse, having, on the ventral 
side, a minute tooth-like process. The cavities of the gills are lenticular, 
placed nearly vertically, having the gills disposed in ridges, in the direction 
of the apertures. The central apertures open into a common duct, by which 
the water entering from the mouth reaches the gills. It is probable, however, 
that Avhile the animal is adhering to any object, and the mouth closed, water 
reaches the gills directly through the lateral or external openings. The her- 
maphroditism of this fish has been pointed out by Sir Everard Home, Phil. 
Trans. 1815, 266. The lamprey leaves the sea, its ordinary residence, and 
enters the larger rivers, during the spring months, for the purpose of spawn- 
ing. The fish, when in season, is esteemed delicious. 
2. P.Jluvmtilis. River Lamprey. — Dusky blue above, be- 
neath silvery. The second dorsal-fin angular, and continuous 
with the tail fin. 
Lampetra fluviatilis, Merr. Pin. 188. — Lampetra, Sibb. Scot. 25. — Will. 
Ich. 104 — P. fluv. Linn. Syst. Nat. i. 394. Penn. Brit. ZooL iii. 79 - 
Lampern, Lesser Lamprey; Nine-eyed eel; IF, Lleprog. — In 
rivers and the sea. 
Length about 10 inches. The first dorsal-fin is angular, and remote from 
the second. The secondary teeth are less numerous than in the lamprey ; 
but, in the absence of specimens, at present, it would be difficult to say more 
on the armature of the mouth, Avithout running great risk of error, especially 
as the descriptions of Artedi, Pennant, Bloch, Lacepede, and Donovan (which 
I have consulted), differ widely from one another. It is probable, that the 
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