Elongate Perciform Fishes — -Gosline 
93 
bone; the ectopterygoid is a minute triangular 
splint at the very base. In Bleekeria the struc- 
ture of the suspensorium is essentially similar 
except that the ectopterygoid is somewhat larger 
so that the palatine does not meet the quadrate. 
The suspensorium of Hypoptychus (Fig. 4a) 
is a quite different structure. The palatine and 
ectopterygoid are about equal in size and are 
united to one another by a digitate suture. The 
metapterygoid is a small splint and the meso- 
pterygoid appears to be absent. 
Undoubtedly the greatest specialization in 
the suspensorium is that found in Crystallo- 
FlG. 4. Right gill covers, suspeosoria, and lower 
jaws, external view, of a, Hypoptychus dybowskii; b, 
Ammodytes tobianus; c, Crystallodytes cookei; and d, 
Tripterygion atriceps (with the lower jaw dislocated). 
an, Angular; ar, articular; de, dentary; ec, ecto- 
pterygoid; hy, hyomandibular; io, interopercle; mt, 
metapterygoid; mx, mesopterygoid; op, opercle; pa, 
palatine; pp. preopercie; qu, quadrate; sb, subopercle; 
and sy, symplectic. 
dytes (Fig. 4c). Here the suspensorium is 
divided into two well-developed and strong 
portions with the ectopterygoid forming a long, 
delicate strut between them. In the anterior 
portion a large, firm mesopterygoid forms a 
shelf under a large part of the eyeball; it is 
firmly attached to the strong palatine anteriorly, 
but only by membrane to the ectopterygoid. 
SKULL: In all of these fishes, there are no 
frontal-parietal crests, and the minute supra- 
occipital crest does not reach above the skull 
surface. Tripterygion , however, has a fringed, 
backwardly slanted crest running across the 
rear of the skull. This crest lies just behind the 
tabular ossicle on each side which bears the 
apparently incomplete supratemporal sensory 
canal commissure. ( In the related Entomacrodus 
the supratemporal commissure is almost com- 
pletely enclosed in the skull. Laterally, the com- 
missure passes through a tabular ossicle that 
is fused to the cranium and thence medially 
through the rear of the parietals, leaving a large 
opening on the middorsal line.) 
In Parapercis and Tripterygion the crania are 
somewhat more highly arched over the orbit 
than in the others. Probably in association with 
this, the wings of the parasphenoid extend 
farther up the sides of the postorbital bar than 
in the remaining four fishes. In all, however, 
the prootic extends over the top of the para- 
sphenoid wings to the edge of the orbit. (In 
Istiblennius, related to Tripterygion, the para- 
sphenoid wings meet the frontals in the usual 
blennioid fashion.) 
In Ammodytes and Bleekeria the two exoc- 
cipital condyles lie adjacent to one another and 
form the upper portion of the facet for the 
articulation of the convex head of the first 
vertebra. In the other forms, including Hypo- 
ptychus, the exoccipital condyles lie at either 
side of the basioccipital articulation; the two 
exoccipital bones do not meet below the fora- 
men magnum; and there is no rounded articu- 
lar head on the first vertebra. 
GILL ARCH SYSTEM: In Ammodytes the bran- 
chiostegal ray count is 8-7; in Crystallodytes, 7; 
in Bleekeria , 7; in Parapercis and Tripterygion, 
6; and in Hypoptychus, 4-4. 
In all the fishes under consideration the lower 
pharyngeals are separate. Ammodytes and 
