CAT-FISHES. 
453 
such as the one represented by the eel-like cat-fish, have additional breathing- 
organs ; in this particular instance taking the form of a branched structure attached 
to the gills. On the other hand, in the sac-gilled cat-fishes ( Saccobranchus ), there 
is a long sac running down the muscles of the back behind the proper gill-chamber. 
Through this breathing-sac blood is carried from and returned directly to the 
heart; and in consequence of this arrangement these fishes can remain alive for 
hours or even days apart from water, so that they are able to traverse spaces 
where aquatic respiration is impracticable. Among the Indian representatives of the 
family it is somewhat curious that whereas most of the forms dwelling far in the 
interior of the country near and in the hills have the air-bladder ossified, this is 
not the case with those inhabiting the rivers of the plains and the sea. The 
majority of the cat-fishes are inhabitants of the fresh waters and estuaries of the 
tropical and subtropical regions of the globe; but, as we have seen, one species is 
found in those of Eastern Europe, while a considerable number enter the sea, 
although generally keeping near the coasts. They are found not only in rivers, 
but likewise in lagoons and marshes. Day writes that ;i they mostly prefer muddy 
to clear water, and the more developed the barbels the more these fishes appear to 
be adapted for an inland or muddy fresh-water residence. The wider and deeper 
the rivers, the more suited they are for the Siluridce, consequently the larger forms f 
are comparatively rare in the south of India, whilst they abound in the Indus, 
Jumna, and Ganges, as also in the Irawadi and other Burmese rivers.” It may be 
added that they are equally common in the muddy waters of the La Plata River. 
“ Owing to their usual resort,” continues the same writer, “ these fishes appear to 
employ their feelers in moving about in muddy places, and consequently have less 
use for their eyes than forms that reside in clear pieces of water. This is one 
reason why the size of the eye as compared with the length of the head is much 
greater in the young than in the adult. The eye, in fact, atrophies, instead of 
increasing in size in proportion with the remainder of the head. In some species 
the skin of the head passes over the eye without any trace of a free orbital margin. 
In the genus Arius, and some allied marine forms, the males appear to carry their 
ova in their mouths, perhaps until the young are produced. Many of these fishes 
are credited with causing poisonous wounds, and we frequently find such cases 
admitted into hospitals. The injuries may be divided into two classes, namely, those 
in which the wounds are of a distinctly venomous description, and those in which 
the jagged spines occasion intense inflammation, often of a dangerous character.” 
The flesh of the cat-fishes is of an inferior quality, and generally eaten only by the 
lower classes. All the members of the family are very tenacious of life, and 
extremely difficult to kill. Geologically cat-fishes date from the lower Eocene 
London Clay, where they are represented by the extinct BucJclandium, apparently 
allied to an existing African genus; while in the higher Eocene of the south of 
England there occur species referred to the existing genus Arius. An extinct 
genus has also been described from the Eocene of North America; and in the 
Eocene of Sumatra, as well as in the Pliocene of India, the fossil forms belong to 
existing genera, and some of those from the latter deposits even to species still 
inhabiting the same country. Numerically the cat-fishes form an exceedingly 
large family, the existing types constituting considerably over a hundred genera, 
