56 
area extends posteriorly to just beyond the tip 
of the pelvic fins but is not as wide as the pelvic 
fins; the size of the area is variable but is always 
larger than in other populations. A vertical strip 
in the axil, about one-half an eye diameter wide, 
is also without scales. Further, the strip of scales 
on the nape is shorter than in the other popula- 
tions (Barlow, 1961a) . The base of the caudal 
fin rays has two to six vertical rows of scales 
on it. In this respect only, the Salton Sea fish 
occasionally are more fully scaled than those of 
the other populations. 
PACIFIC SCIENCE, Vol. XVII, January 1963 
populations tends to converge in the lower lati- 
tudes. 
The mean number of dorsal fin rays in the 
Salton Sea population is greater by about one 
ray than in the other populations. 
The large range and variation of the New- 
port Bay population are caused chiefly by one 
specimen with only eight rays. The fin does 
not look aberrant but it must be considered 
atypical. 
Anal Fin 
First Dorsal Fin 
The average spine number is about six for 
all populations, although some means deviate 
appreciably from this value (Fig. 6). The count 
never was found to be less than six in Gulf 
populations. Five spines, however, are not un- 
common in other populations. The only geo- 
graphic trend discernible concerns the variances 
of the populations; this is reported below. 
Second Dorsal Fin 
The mean number of rays in the second dor- 
sal fin is clearly higher in Pacific Coast than in 
Gulf populations (Fig. 6). On the Pacific Coast 
the counts are lower in the south, while in the 
Gulf the counts are more nearly uniform, or 
slightly higher in the south. Thus the average 
number of fin rays for Gulf and Pacific Coast 
On the Pacific Coast the mean number of 
anal fin rays increases from the north, south to 
San Diego, then decreases further south. In the 
Gulf, where samples are less complete, the 
means are about the same in all populations, 
or are a little higher in the south. The means 
of the Gulf and Pacific Coast populations con- 
verge in the lower latitudes (Fig. 7). 
The mean number of anal fin rays in the fish 
from the Salton Sea is conspicuously higher 
than in any of the naturally occurring popula- 
tions ( Fig. 7 ) . 
Pectoral Fin 
The mean number of pectoral fin rays in- 
creases progressively from north to south on 
the Pacific Coast, but in the Gulf of California 
the average number decreases to the south. Con- 
sequently, the means of Pacific Coast and Gulf 
FIG. 5. Gillichthys mkabilis, female, standard length 100 mm, from "El Marino” slough north of San 
Felipe, Baja California. The small black spot on the side of the specimen is a blemish. 
