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 " 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 Silwridce, consequently the larger forms 

 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 Bucklandium, 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, 



