99 FISHES OF SINALOA. 471 
a substitute for Gerres, regarded as preoccupied by the 
earlier name Gerrzs, applied by Fabricius to a genus of 
insects. The name Catochenum can only be used if 
Gerres is regarded as ineligible. By the rules followed by 
‘us, Gerres must be retained, being spelled differently from 
Gerrts. In different publications of Poey, plumzer? is 
made the type of Gerres, although it is not one of Cuvier’s 
original species. Bleeker substitutes Dzapterus tor Ger- 
res and Catochenum, specifying Plumzer7 as its type, while 
Gill and Poey have used the name Dzapterus for the allies 
of gula, to which the name Hucrnostomus had been applied 
in 1855 by Baird and Girard. Although A/wmer¢ cannot 
be made the type of Gevres, it seems to us that the cog- 
nate species /7zeatus can be so regarded. If this view is 
adopted, the restricted Gevres of the present paper would 
correspond exactly with the restricted Gervres of Poey and 
Gill. This fact certainly justifies us in choosing /7neatus 
as the type of the genus. 
There can be no doubt of the generic value of Auczn- 
ostomus (gula) and of Ulema Jordan & Evermann MS. 
(lefroy:), as distinguished from Gerres. Of the other 
groups represented in American waters, \ystema Jordan 
& Evermann MS. (ccnereus) seems to be a valid genus, 
while Diapterus (auratus) should stand rather as a sub- 
genus of Gerres. Duapterus difters from Gerres chiefly 
in the entire preorbital. Xystema has the preopercle as 
well as preorbital entire, while U//ema has the second in- 
terhemal very short, and the two spines of the anal are 
themselves scarcely enlarged. 
Moharra Poey (rhombeus ) difters from Diapterus only 
in the presence of two anal spines instead of three, a 
character of low importance, as the relation of the species 
included in the two groups is very close. 
The exotic genera of this group have not been studied 
by us. 
