FAMILY PETROMYZONID&. 383 
GENUS AMMOCC:TES. Dumeril. 
Mouth without teeth. Upper lip prominent, semicircular, covering only the upper part and 
sides of the mouth ; lower lip transverse. Branchial apertures as in the preceding. 
THE COLORED MUD LAMPREY. 
AMMOCGTES BICOLOR, 
PLATE LXXIX. FIG. 248. 
Ammocates bicolor, LEsurur, Am. Phil. Soc. New Series, Vol. 1, p. 386. 
The Mud Lamprey, A. bicolor. Storer, Fishes of Massachusetts, p. 198. 
Characteristics. Back and sides reddish, separated by an undulating line from the white abdo- 
men. Dorsals separated. 
Description. Anterior part of the body subcylindric ; posterior part compressed, and taper- 
ing to the tail. Dorsals low, separated; the second united with the caudal fin, which is 
rounded. Nape of the neck elevated. Head declivous, prolonged into a snout, furnished 
with a lip, having two short rounded lobes ; these lobes, when the mouth is closed, embrace 
and conceal the lower lip, which is very short. Nostrils small, and placed in the centre of a 
white oval pellucid disk, easily movable. On the inside of the upper lip, small granules ; 
and at the opening of the throat, small ramified papille. Branchial apertures placed in a 
longitudinal depression, oblique and a little curved ; the first aperture above the angle of the 
mouth. On each side of the head there is a whitish spot, indicating the position of the eyes. 
This species was first described by Lesueur, from the Connecticut river, near Northampton, 
but has not since been observed. 
THE PLAIN MUD LAMPREY. 
AMMOCG@TES UNICOLOR. 
PLATE LXXIX. FIG. 250.—(STATE COLLECTION.) 
Characteristics. Color nearly uniform throughout. Dorsal single. Length three to five 
inches. 
Description. Form cylindrical for two-thirds of its length from the head, becoming slightly 
compressed just anterior to the vent, very much compressed and acuminated at the tail. Sur- 
face smooth, with between eighty and ninety transverse folds, giving the body an annulated 
appearance. Nape arched; headsloping to the anterior lip. Mouth quadrilateral. Opening 
to the throat very large, but accurately closed by six irregular and ragged subcartilaginous 
processes, which meet in the centre. Anterior lip transverse, convex on its outline, and 
emarginate at each end, where it unites with the lateral lips ; these latter are wide and convex 
