FAMILY PETROMYZONID^, 383 



GENUS AMMOCCETES. 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. 



Ammoccetes bicoi.or. 

 plate lxxix. fig. 248. 



Ammocales hkolor. Lesdeor, Am. Phil Soc. New Series, Vol. 1, p. 386. 

 The Mud Lamprey, A. bicolor. Stoker, Fishes of Massachusetts, p. 19S. 



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 papilla;. 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. 



Ammoccetes unicolor. 

 plate lxxix. fig. 550. — (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 ; head sloping 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 



