Elongate Perciform Fishes— Gosline 
91 
Fig. 1. Sketches of a, Bleekeria gilli, from Gosline 
and Brock, after Fowler, based on a specimen 3 inches 
in total length; b, Crystallodytes cookei, based on a 
specimen 2 inches long; c, Parapercis schauinslandi, 
from a 3 -inch specimen; and d, T riptery gion atriceps, 
from a 1-inch fish. 
parison with the three ammodytoids and in 
an attempt to obtain some understanding of 
the lineages to which each of them belongs. 
With regard to these six fishes that have been 
investigated in some detail, it may be stated 
in advance that the author has not had any 
great success in discovering significant cranial 
differences between them. It is not so much 
that such differences do not exist, as that they 
appear to have rather slight systematic value. 
Though it may be that the author has simply 
overlooked significant differences, it would ap- 
pear that the percoids and their immediate 
derivatives have a rather standardized skull pat- 
tern and that the major morphological differen- 
tiation of percoid groups has occurred in other 
features. 
lacrimal (preorbital) followed by about five sepa- 
rately movable, canal-bearing ossicles (cf, Ka- 
tayama, 1959: figs. 2-5). Above the fifth, 
the infraorbital lateral line canal joins the 
supraorbital canal. Of the five ossicles the upper- 
most is particularly variable and is sometimes 
fused to and sometimes free from the sphenotic. 
In Parapercis (Fig. 2a) the infraorbital 
canal is complete, passing through a lacrimal 
and six separate circumorbital bones. The upper- 
most of these is firmly attached to the cranium 
in Parapercis. Because six circumorbitals ap- 
peared to be a high number, the opposite side 
of the same specimen and of a larger specimen 
of Parapercis schauinslandi were checked; no 
variation was found. The circumorbital struc- 
tures of T riptery gion differ from those of Para- 
percis in having three instead of six circum- 
orbital bones and in the failure of the bone to 
close over the sensory canal externally. In Crys- 
tallodytes the circumorbital canal is still com- 
plete but there are only a lacrimal and two 
circumorbitals. The lacrimal and second circum- 
orbital are large and laminar, but the anterior 
circumorbital is quite small. 
In Ammodytes (Fig. 2b) there is a large 
lacrimal, followed immediately by a moderate- 
sized first infraorbital; then there is a broad 
gap followed by two small circumorbitals, the 
HEAD SKELETON 
CIRCUMORBITAL BONES: In the typical per- 
coid the circumorbital series is made up of the 
FIG. 2. Lacrimal and circumorbital bones of a, Para- 
percis schauinslandi, and b, Ammodytes tobianus. 
There are no circumorbital bones bordering the por- 
tion of the orbit indicated by the dashed line in 
Ammodytes. co, Circumorbital bones; and la, lacrimal. 
