SYNOPSIS. 423 



the hinder part of the body forming a dorsal, anal, and caudal 

 fins. 



Sp. 248. P. niarhms. Lamprey. Body eel-like, compressed 

 and shghtly tapering behind ; two dorsal fins, the second 

 most elevated, and separated from the caudal; skin smooth, 

 the colour olive-brown mottled and spotted with dark 

 green and dark brown ; edges of the fins reddish brown. — 

 — Linn., Penn. Brit. Zool., iii. p. 102, pi. 10 ; Don. Brit. 

 Fish, pi. 81 ; Yarr. Brit. Fish., ii. 598. 

 Sp. 249. P. fiuviatUis. River Lamprey. Body more elon- 

 gated in proportion than that of P. marinus; end of the 

 taU compressed ; dorsals widely apart, the posterior one 

 angular and united to the caudal ; anal also united to the 

 caudal ; colour dusky blue above, silvery white beneath. 

 — lAnn., Cuv. Reg. An. Lesser lamprey, Penn. Brit. ZooL, 

 iii. p. 106, pi. 10 ; 2)(wi. Biit. Fish., pi. 54 ; Yarr. Brit. 

 Fish., ii. 604. 

 Sp. 250. P. PlajieH. Planer's Lamprey. Lip broad and 

 fringed ; first dorsal beginning about the middle of the 

 whole length of the fish, and in close contact with the 

 second ; anal fin rudimentary ; colours nearly as in P. 

 Jluviatilis. — Bloch, pt. iii., pi. 78, fig. 3; Jenyns'' Brit. 

 Vert., 522 ; Yarr. Brit. Fish., ii. 607. 

 Gen. CXXIII. Ammoccetes. Each side of the neck with 

 seven branchial openings ; lip semicircular, under lip straight 

 and transverse ; teeth wanting, their place supplied by memi 

 branous cirri. 



Sp. 251. A. hranchialis. Pride or Mud Lamprey. Eye 



very small ; body cylindrical, compressed behind the anal 



opening ; two dorsals, first low, separated from the second ; 



caudal rather rounded ; colour yellowish brown, darkest 



on the back and lighter beneath, but liable to variation. 



— Cuv. Peg. An. ; Jenyns'' Brit. Vert, 522 ; Ymt. Brit. 



Fish., ii. 609. Petromyzon branchialis, Linn. 



Gen. CXXIV. Gastrobranchus. Branchial openings two 



in number, placed under the commencement of the belly ; lips 



surrounded with eight cirri, the mouth with one hook-like 



tooth ; tongue with two rows of teeth on each side. 



