210 [September, 



which anterior margin of the dorsal, is nearer to the tip of the snout than the 

 base of the central rays of the caudal. 



D 2+9; A 2+9; C 5, 1, 9, 8, 1, '7 ; V 8 ; P 15. 



There are thirty-eight scales in the lateral line ; six longitudinal rows above 

 it, and four beneath, upon the line of greatest depth. Color brownish red 

 above, pale reddish beneath ; flanks shining of silver and gold. 



Inhabits the Potomac River, and probably all the fresh waters of Maryland. 

 It is commonly called Smelt, at Washington and vicinities, and Gudgeon at 

 Baltimore and surrounding counties. 



2. Hybognathus nitidus. Leuciscus nitidus, Dekay, N. Y. Fauna, iii. 1842, 

 209. PL xxxiii. fig. 105. Storer, Synops. 1846, 162. 

 Collected at Westport, Lake Champlain. S. F. Baird. 



HUDSONIUS. 



Body elongated, compressed, fusiform in profile, and covered with quite large 

 scales. The lateral line being nearly medial. The head is of but moderate size ; 

 the snout being subconical and rounded anteriorly. The mouth is subterminal, 

 somewhat protractile, in which situation it is directed obliquely forwards and 

 downwards ; when shut, the lower jaw fits within the upper, the snout being 

 slightly protruding. There are no barbels about the mouth. The eyes are large ; 

 the isthmus is small. The dorsal is higher than long ; its anterior margin is even 

 with the insertion of the ventrals. The anal has a proportionally longer base 

 than the dorsal. The caudal is deeply furcated. The pharyngeal bones are 

 well developed ; the inferior limb is rather short, its extremity being flattened 

 and slightly turned outwardly. From the middle of the convexity a sudden 

 expansion occurs, tapering into the upper limb, slightly curved downwards. 

 The teeth are of the bruising kind, of the hooked type, provided with a grinding 

 surface. But there occurs many irregularities, being more or less hooked and 

 the grinding surface more or less developed. It is not uncommon to observe 

 all these variations upon the pharyngeal of a single specimen. The teeth are 

 disposed upon a double row with the following variations : 2 | 4 4 | 2, 

 2 I 44 I 1, 1 44 I 2, or I 44 | 1. 



1. HuDSONius FLUviATiLis. Clupea Imdsonia, Clinton, Ann. Lye. Nat. Hist. 

 N. Y. I. 1824, 49. PI. ii. fig. 2. Leuciscus hudsonius, Dekay, Fauna, of N. Y. 

 III. 1824, 206. PI. xxxiv. fig. 109. Storer, Synops. 1846, 157. Agass. Lake 

 Sup. 1850, 272. 



Specimens collected in Chicago Harbor, Lake Michigan, and in the Root 

 River, at Racine, Wise. S. F. Baird. 



2. HuDSONius AMARUS. This species is closely allied to the preceding, 

 from which it diS"ers by a smaller head and smaller eye. Its opercle is 

 also broader compared to its height or depth. The head constitutes the sixth 

 of the total length. The greatest depth taken immediately in advance of the 

 dorsal, enters a little over five times in the total length. 



The coloration is nearly the same as in Jl.fluviatUis, with the exception that 

 the black snot at the base of the tail disappears at a much earlier period. The 

 species grows to a much larger size also ; we have seen specimens seven inches 

 long, in which the satin band along the sides and the black spot of the tail had 

 given way to a uniform golden hue extending to nearly the entire body. 



Caught in Chesapeake Bay, and as far up the Potomac River as Washington, 

 where it is caught along side with Hijhognathus regius, and similarly called 

 Smelt. 



Hybopsis, Agass. 



This genus was left rather vaguely defined by its author, for there are many 

 genera in which "the mouth is protractile downwards, after the fashion of 

 Catostomus" with the lips neither swollen nor thickened. And many other genera 



