LOACHES. 
703 
Fam. cobitid^e. 
Air-bladder more or less reduced , entirely or partly enclosed in an osseous capsule. Mouth fringed with, six or 
more barbels. Pseudobranchice wanting. 
This family was established under the name given 
above by Bonaparte" in 1846, but subsequently re- 
ceived of Heckel and Inner/' the name of Acanthopsi- 
des, derived from the generic title which Agassiz had 
supposed to be deserved by our most common species. 
By most authors, however, the family has been regarded 
as a subfamily among the Cyprinoids. Still it possesses 
so many distinctive characters that it may well main- 
tain its position in the system. The most prominent 
among these characters are those which suggest an 
alliance with the Glanomorph series. Among these we 
find externally the slimy skin, generally naked, other- 
wise with small scales, and the comparatively numerous 
barbels round the mouth; while internally the capsule 
of the air-bladder reminds us of the corresponding 
structure in many of the Glanomorphs, and the ossifica- 
tion of the head shows a fronto-parietal fontanel simi- 
lar to that we have remarked above in the Siluroids. 
The intestinal respiration of the Cobitoids may also 
be in some degree a trace of their connexion with the 
preceding series of forms, where we have seen the 
respiration of air accomplished in various ways, and 
where the respiration of water seems in certain fishes 
to be assisted by an apparatus consisting of ramified 
appendages in the anal region. In the present series, 
on the other hand, it has long 0 been known that under 
certain circumstances, where there is scarcity of water 
or of the oxygen contained therein, our European Co- 
bitoids ascend to the surface and swallow air, which 
they audibly eject after a time through the vent, with 
the oxygen now changed to carbonic acid gas. 
The Cobitoids are distinguished from the following 
family not only by the capsulate air-bladder and the 
greater number of the barbels, but also by the absence 
of pseudobranchige — this is also the case in the great 
majority of the Glanomorphs — and the comparatively 
small size of the gill-openings, the branchiostegal mem- 
branes being united underneath for the greater portion 
of their length to the isthmus. The lower pharyngeals 
are destitute of the strength which they possess in the 
following family, are more like branchial arches, and 
are armed with a row of weaker, but in general more 
numerous teeth. 
The air-bladder is partly free, it is true, in several 
fishes of this family, a posterior division thereof lying 
free within the abdominal cavity. But in others, and 
in particular in all our European species, it is com- 
pletely enclosed in a porous or retiform, osseous cap- 
sule, or only a small, rounded expansion of the air- 
bladdeW juts out at the hind orifice of the capsule, 
where otherwise only the pneumatic duct descends to 
the oesophagus. The osseous capsule of one of the 
European species, Cobitis ( Misgurnus ) fossilis , is excel- 
lently described and figured by Weber (1. c.). Its 
morphological explanation consists in a tumidity and 
transformation of the osseous structure originally be- 
longing to the lower and inner parts of the transverse 
processes of the third vertebra and to its pair of ribs. 
The upper and outer (dorsal) part of this transverse 
process on each side may still be distinguished in the 
wall of the capsule; and in our Spined Loach ( Cobitis 
taenia ;) the top of this process, as tvell as each of the 
ribs behind it, bears a scleral (epipleural, muscular) 
bone branched at the top. The osseous point that, pro- 
jects downwards on each side of the capsule, also pre- 
sents an unmistakable resemblance to the ends of the 
ribs behind this point. The same explanation is given 
of the hollow bone extending from each side of the 
body of the second vertebra and from the lower part 
of its neural arch, backwards, outwards, and down- 
wards, above the anterior upper part of the surface of 
the osseous capsule. Within this hollow bone are con- 
tained the so-called acoustic bones. In the Spined Loach 
this hollow bone — the outcome of the material of the 
a Cat. Met. Peso. Europ. pp. 5 and 26. 
b Siisswasserf. Oesterr. Mon ., p. 296. 
c See Erman i Gilbert’s Annalen der Physik, Bd. XXX (1808), p. 140. Cf. also Siebold, Siisswasserf. Mittelenr., p. 340. 
d See Weber, De Aure etc., tab. VI, fig. 48, sign. 8. 
Scandinavian Fishes. 
89 
