Petromyzon. FISHES. CHONDROPT. 163 



CHONDROPTERYGIOUS 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 fins disjoined. 



Lampetra, Merr. Pin. 188 — L. Rondeletii, Will. Ich. 105. — P. mar. Linn. 



Syst. i. 394. Penn. Brit. Zool. iii. 76. — E, Lamprey Eel ; W, 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 papilla?, 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, with 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 while 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 ponited 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.JluviatiUs. River Lamprey. — Dusky blue above, be- 

 neath silvery. The second dorsal-iin 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.— 



E, Lampern, Lesser Lamprey ; £, Nine-eyed eel ; W, Lleprog — In 

 rivers and the sea. 



Length about 10 inches. The first dorsal-fin is angular, and remote froni 

 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, without 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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