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PROFESSORS T. W. BRIDGE AND A. C. H ADDON 
anterior continuation of the mesonephros traverse a foramen in the anterior wall of 
the funnel situated ventrad to that which transmits the tripus. On the left side both 
the groove and foramen are very feebly developed. In the proximal portion of the 
right funnel there is a short dorsal lamina passing from the ventral surface of the 
transverse process of the fourth vertebra, ventrad to the cardinal groove, to unite 
with a well-marked radial nodule, but the latter is in close contact with the lateral 
surface of the complex centrum, and is somewhat loosely united thereto by fibrous 
tissue. On the left side, through the narrowness of the cardinal groove, the dorsal 
lamina is very short, and, with the radial nodule, is firmly attached to the side of the 
complex centrum. 
In shape and structure, and in the nature and extent of its attachments to the walls 
of the osseous capsules and to the tripodes, the air-bladder of Saccohranchus closely 
resembles that of Clarias. An intermediate tubular portion connects the two lateral 
air-sacs, and is in communication with the oesophagus by a ductus pneumaticus. 
The scaphium has a very short rudiment of an ascending process in addition to a 
condylar process. An intercalarium is present in the form of an extremely thin 
discoidal ossicle, imbedded in the interossicular ligament. The tripus (fig. 83, a) has 
a more normal shape than in Clarias, but its crescentic process is an exceptionally 
thin, wide, curved lamina of imperfectly ossified bone. 
Silurus glanis. 
We have but little to add to the description of this species which Weber gave in 
his classical memoir, “ De Aure et Auditu Hominis et Animalium, Pars i., De Aure 
Animalium aquatilium.” On Plate V. of this memoir Weber has given accurate 
figures of the membranous labyrinth and “ ossicula auditus.” The anterior vertebrae 
and their processes are also figured, but as Weber failed to recognise the fusion of 
the second, third, and fourth vertebrae to form the “ complex ” vertebra the nomen- 
clature he applied to them is inaccurate. 
Except for the absence of a fan-shaped subvertebral process, Silurus closely resembles 
Plotosus in most of the osteological details with which we are now concerned, and 
also in the condition and skeletal relations of its air-bladder. The latter organ 
(fig. 84) is well developed, and its walls are fairly thick though somewhat thinner, 
perhaps, in the anterior chamber than elsewhere. In young specimens of from four 
to six inches in length the bladder is rather long in proportion to its width, but in 
older specimens it becomes somewhat broader and relatively shorter, and in the adult 
assumes the usual conical shape. The transverse septum (t.s.) is a narrow but stout 
vertical pillar of fibres, continuous behind with the longitudinal septum (l.s.) between 
the two lateral compartments. A transverse membrane with the usual lateral and 
dorsal attachments to the skeleton is closely applied to the anterior wall. A thin 
