186 
PROFESSORS T. W, BRIDGE AND A. C. HADDOX 
The true posterior process of the clavicle (fig. 75, cl.p.), instead of marking the 
inferior boundary of a lateral cutaneous area, is directed backwards on the ventral 
side of the body and related solely to the insertion of the ventro -lateral muscles of 
the body-wall. 
The air-bladder (fig. 76, a.h.) is partially constricted into two laterally situated 
and somewhat ovoid or globose sacs by deep emarginations in its anterior and 
posterior w’alls.''^ Each half of the bladder occupies the shallow bony recess formed 
by the modified transverse processes of its side. Nearly the whole extent of the 
lateral or outer wall of each sac, as well as a part of the dorsal wall, are in close 
contact with the inner surface of a lateral cutaneous area. The opening of the 
ductus pneumaticus {d.p.) is in the medio-ventral line, but nearer to the anterior than 
the posterior end of the bladder. On removing the ventral wall (fig. 77) it at once 
becomes obvious that the lateral portions of the organ are in free and open communi- 
cation with each other, and further, that by far the larger portion of the bladder 
corresponds to the anterior chamber only of the normally developed structure. A 
very narrow transverse septum {t.s.) is present, but situated so near to the posterior 
wall that there exists but the barest vestige of a longitudinal septum {l.s.), and if 
lateral compartments can be said to be represented at all it can only be by the 
postero-internal portions of the lateral halves of the bladder. 
In the general structure of the walls of the bladder, which it may be mentioned 
are extremely thin, and in the nature and extent of its various skeletal attachments, 
Aspj'edo differs in no essential feature from Macrones. The transverse septum is 
attached dorsally to the ventral surface and sides of the body of the fifth vertebra, 
and anteriorly and laterally to this to the posterior margins of the dorsal laminae. 
The anterior pillars are inserted by their dorsal edges into the radial nodules, as well 
as to the lateral and ventral surfaces of the anterior portion of the complex centrum, 
and the fibres of the two strata of the tunica externa in converging from the antero- 
lateral and lateral walls to their attachments to the crescentic processes of tlie 
trlpodes {tr.c.) form the usual well-defined triangular sheets (fig. 77). 
The tripus (figs. 73, 77, tr., tr.c.) has a short inwardl}7--curved crescentic process, 
and a I’elatlvely long anterior process. The Intercalarium is a very small nodule in 
the interosslcular ligament. The scaphium has no ascending process, but is other- 
wise complete. The claustra are extremely small spicular ossicles in the usual 
position. 
The recesses for the saccull are unusually shallow, and the cavum sinus imparis is 
relatively shorter than in most other Siluridse. The atrial cavities are normal, except 
that their external apertures and the scaphia which close them, as well as the inter- 
ossicular ligament, lie altogether within the neural canal on the dorsal surface of the 
• The width of the bladder in oar specimen was 17 mm., and the length of each half 10 mm. The 
length of the Fish was 6 inches. 
