52 
PACIFIC SCIENCE, Vol. XVII, January 1963 
TABLE 2 
Fin Counts for Gillichthys mirabilis, MATERIALS AND LOCALITIES 
°N 
LOCALITY 
COLLECTED 
FIN COUNTS 
n (SIZE RANGE) 
Pacific Coast 
37°27' 
San Francisco Bay 
June 1957 
30(39-86) 
35°20' 
Morro Bay 
August 1957 
30(86-132) 
34°24' 
Goleta 
September 1957 
30(64-125) 
34°00' 
Venice 
June 1957 
28(83-138) 
33°37' 
Newport Bay 
October 1955 
25(56-154) 
33°01' 
San Elijo Lagoon 
June 1956 
30(58-142) 
32°47' 
Mission Bay 
May 1946 
30(38-54) 
31°43' 
Estero Punta Banda 
July 1955, 1956 
20(80-124) 
30°30' 
Bahia San Quintin 
July 1956 
14(91-142) 
26°45' 
Punta Abreojos 
May 1948 
16(10-20) 
24°47' 
Bahia Sta. Maria 
April 1955 
30(22-38) 
Salton Sea 
33° 18' 
NW Shore 
July 1953 1 
30(55-109) 
NE Shore 
July 1954 1 
30(40-78) 
NW Shore 
July 1955 
30(35-74) 
Gulf of California 
31°2 r 
Bahia Cholla 
January 1949 
30(20-30) 
Bahia Cholla 
April 1954 
30(48-88) 
31 ° 18' 
San Felipe 
April 1957 
31(25-50) 
27°57' 
Estero Soldado 
January 1952 
31(15-20) 
26° 54' 
Mulege 
March 1957 
30(35-50) 
26°22' 
Bahia Agiabampo 
January 1951 
10(66-100) 
1 Not included in Figures 6-12. 
shape is due largely to the more depressed head 
of the Gulf fish, and was one of the main reasons 
for naming this form as a new species. In their 
description, Gilbert and Scofield (1898: 498) 
commented on the depressed head of Gillichthys 
detrusus ( = G. mirabilis Cooper ) . This condi- 
tion prevails in all the populations investigated 
from the Gulf. The mean head depth for fish 
from "El Marino” slough, just north of San Fe- 
lipe, is 15.6% (13-18%; n = 10) of standard 
lenth, which agrees nicely with the value for 
Bahia Agiabampo fish (Barlow, 196L*). It 
should be noted at this point that the position 
of the opercles and the branchiostegals of pre- 
served gobies can cause considerable variation 
in measurements of head depth and especially 
of head width. 
The head shape of Salton Sea fish is more like 
that of specimens from the Pacific Coast than of 
those from the Gulf. The measured head depth, 
though, is closer to that of Gulf populations 
(Barlow, 196 1^). 
The regression of head length on standard 
length is slightly, but significantly, greater for 
the Pacific Coast populations than for the fishes 
from the Gulf when the data are pooled (Fig. 
2, Table 3). Along the Pacific Coast the five 
populations also differ significantly from one 
another ( Table 3 ) . The differences between 
Gulf populations are of approximately the same 
degree as those between the Pacific Coast groups, 
but this was not tested statistically. Fish from 
the Salton Sea have the shortest heads, which is 
immediately noticeable when inspecting large 
adults. 
Relative growth differences are seen best by 
plotting the logarithms of head and standard 
length (Martin, 1949: 8). The regressions for 
all populations so presented are nearly parallel 
(no figure) . These curves for relative growth of 
the head, however, are slightly but clearly curvi- 
linear; the slopes steepen with increasing stand- 
ard length. The relative degree of difference 
between any of the lines is the same for the 
