18 CONTRirJUTIONS TO NORTH AMERICAN ICHTHYOLOGY III. 



surface is more or less ereuate, especially' in young individuals; (c) (he 

 aual flu is always short, containing from seven to nine rays; (rf) tbo 

 dorsal tin is never inserted very far behind the ventrals; (c) the lateral 

 line is developed and continuous. 



The species dififer much among themselves in size, nuptial dress, and 

 general appearance, notably in the squamation, the scales of the typical 

 species of Lurilus being closely imbricated and much higher than long, 

 wiiile in the group called Jluflsonins the two dimensions of tlii' scales are 

 nearly eipial. The sciales themselves, in Hudsonius, are thin and loosely 

 imbricated. Within certain limits, the position of the dorsal varies also. 

 In Hudsonius, its first ray is in advance of the insertion of the ventrals; 

 in Luxilus ami AlbHnio2)s, usunWy directly oi)posite; in Photogenis and 

 HydrophloXy distinctly posterior. The form of the mouth varies largely : 

 in L.coccogenis, it is wide and oblique, the lower jaw projecting. In 

 the typical species of Alhurnops and Hudsonius, the mouth is small and 

 more or less inferior. 



The species may be provisionally grouped as follows, under live groups, 

 four of which may be considered as distinct genera. Those species 

 whose position is doubtful are indicated by a mark of interrogation : — 

 A. — LuxiLUS Rofinesque. (Scales very closely imbricated, much deep- 

 er than long: teeth2, 4-4, 2, entire: dorsal 15n inserted directly op- 

 posite ventrals: mDUth termiiuil : size large: nui)tial dress 

 peculiar ; type Cijprimis cornutus Mit.) 



cornuius Mit. coccogeuis Cope. 



selene J or. 

 r>. — PnoTOGENis Cope. (Scales pretty closely imbricated, deeper than 

 long: teeth 1, 4-4, l,morc or less ereuate (rarely one-rowed ?): 

 dorsal fin behind ventrals, always with a black spot on the last 

 rays behind : males in spring tuberculate, the lower fins ami the 

 tips of the vertical fins filled with satin-white pigment in spring: 

 mimtli terminal, the upper jaw longest: size medium; type l\ 

 spilopfcrus Cope = CyprincUa anahstana). 



analosfauus Girard. nireus Cope. 



galacturus (^ope. iris Cope (?). 



Icucopus .1, »S: H. 

 C. — IIydrophlox Jordan. (Scales less closely in)l>ricated, somewhat 

 deeper than long; teeth usually 2, 4-4, 2, often more or less 

 ereuate: dorsal fin distinctly behind ventrals, unsjiotted : breed- 

 ing dress peculiar, thema'es almost always red : mouth terminal, 



