BONES OF LOPHIUS PISCATORIUS — MORROW. 345 
on their outer surfaces, and which support the posterior arms of 
the hyomandibulars ; on their inner surfaces they are irregularly 
flattened, and terminate in an acute angle, abutting for more 
than half their length against the ridges which rise from the 
condyles of the quadrates. 
32. The subopercula: these are of very peculiar form, and 
are attached to the anterior faces of the ridges on the opercula 
bones for rather more than one-half the length of the latter ; they 
decrease in size as they rise, terminating in flatted points which 
lie close to the opercula; from them extend anteriorly long pro- 
cesses to which fibrous tissue is attached, forming the connection 
between these bones, the subopercula and epihyals; posteriorly, 
they are produced into long, fin-like rays, sixteen to eighteen in 
number,connected by membrane, which gives them a strong resem- 
blance to a fin. At the bases of their anterior processes there are 
two of the so-called spines. The inferior extremities of the oper- 
cula bones extend a little beyond the solid part of these bones, 
and to about one-third of the breadth, when extended, of the 
fin-like rays. 
33. The interopercula are somewhat triangular in shape, hav- 
ing upon their superior outer extremities peculiarly-shaped pro- 
cesses, to which, at their inner edges is attached the thin tissue 
connecting them with the preopercula and with the long arms of 
the opercula bones (not plates). | From the superior outer edges 
of these bones descend their attachment to the epihyals from 
which thickened branches are sent out to support the anterior 
angular extremities of the singularly-shaped subopercula bones, 
and from their anterior extremities strong ligaments attach them 
to the posterior extremities of the articularies on their inner 
sides, enveloping at the same time the posterior extremities of 
the angulars. These bones lie immediately beneath the preo- 
percula, the ossa sympletica (mesotympanic—Owen) and the pos- 
terior part of the quadrates. 
31. Ossa sympletica (mesotympanic—Owen). These bones lie 
between the metapterygoids, the preopercula and the forks of 
the quadrates. They have double anterior margins for the recep- 
tion of the metapterygoids and the anterior margins of the forks 
