Gillichthys mirabilis — Barlow 
55 
Fig. 4. Anal fin height versus standard length. Gulf 
of California populations: open triangle, San Felipe 
(El Marino); open square, Mulege; open circle, Bahia 
Cholla, 1954; closed triangle, Guaymas (Estero Boco- 
chibampo); closed circle, Agiabampo. Pacific Coast 
populations: closed circle, San Francisco Bay (Alviso 
ponds ) ; open triangle, Goleta; closed square, Newport 
Bay; open circle, San Eli jo Lagoon; closed triangle, 
Estero Punta Banda; open square, Bahia San Quintin. 
Sal ton Sea population: open triangle, 1953; open 
square, 1954; open circle, 1955. 
The anal fin height of Salton Sea fish (Fig. 
4) is considerably lower than in Gulf groups. 
Compared to Pacific Coast populations, the fin 
heights are similar but nevertheless lower. The 
variation in height from year to year in the 
Salton Sea fish is just significant at the 5% level. 
The profile of the second dorsal fin is more 
rounded in specimens from the Gulf of Califor- 
nia than in those from the outer coast or the 
Salton Sea. This results from the relatively 
greater increase in length of the centermost rays 
in the higher fins. Besides the change in shape, 
the anterior height of the second dorsal fin 
equals or exceeds that of the first dorsal in Gulf 
forms (Gilbert and Scofield, 1898: pi. 38). In 
fish from the Pacific Coast and the Salton Sea, 
the anterior rays are lower and the central rays 
are equal to or only slightly higher than the 
spiny dorsal. 
Distance between Dorsal Fins 
The distance between dorsal fins is greatest 
in fish from the northern part of the Gulf of 
California, ranging from 1.0 to 1.8 times the 
eye diameter. The distance between fins of speci- 
mens from the central and southern Gulf is 
about the same as that of fish from central Cali- 
fornia, being 0.7-1. 1 times the eye diameter. 
The distance between dorsal fins was one of 
the diagnostic characters used by Gilbert and 
Scofield (1898: 498) to separate detrusus from 
mirabilis. 
In Salton Sea fish, the distance between fins 
is less than one eye diameter. The posterior 
margin of the first dorsal sometimes touches 
the anterior margin of the second dorsal. A 
greater number of elements in both dorsal fins 
as well as an encroachment on the space by two 
to three supernumerary spines on the leading 
edge of the second dorsal fin cause the decrease 
in distance. 
Squamation 
The scales are slightly larger in specimens of 
mirabilis from the Gulf of California than they 
are in those from the outer coast and the Salton 
Sea. The counts range from 60 to 80 irregular 
vertical rows of scales along the body in Gulf 
forms, while there are about 80-100 rows in 
fish from the Pacific Coast and the Salton Sea. 
The ventral squamation is more extensive in 
fish from the Gulf than in those from the Pacific 
Coast or the Salton Sea. The scales extend an- 
teriorly around the base of the pelvic fin in about 
30% of the specimens from Bahia Agiabampo 
(southern Gulf), in about 10% from Guaymas 
(central Gulf), and in about 80% from Bahia 
Cholla (northern Gulf). In fish from the Pa- 
cific Coast, the scales only occasionally reach 
anteriorly beyond the lateral insertion of the 
pelvic fin base. 
In many respects the scalation is less exten- 
sive in Salton Sea fish, although the scales are 
about the same size as those on fish from the 
Pacific Coast. The ventral, anterior margin of 
the scaled area usually just reaches the insertion 
of the pelvic fins, but not beyond. The scaleless 
area directly under the pelvic fins is greater than 
in naturally occurring populations. The naked 
