s, and both parents remain by the side of the
nest, furiously attacking any assailant.

[Illustration: FIG. 5.--_Loricaria lanceolata_, from the upper Amazons.]

The allied family _Loricariidae_ is entirely confined to the fresh
waters of Central and South America. C.T. Regan, who has recently
published an elaborate monograph of them, recognizes 189 species,
referred to 17 genera. Many of them are completely mailed; but all have
in common a short-rayed dorsal fin, with the ventrals below or rarely
in front of it. Their gill-openings are reduced to a short slit. The
first group of this section comprises alpine forms of the Andes, without
any armature, and with a very broad and pendent lower lip. They have
been referred to several genera (_Stygogenes, Arges, Brontes,
Astroblepus_), but are collectively called "prenadillas" by th natives,
who state that they live in subterranean craters within the bowels of
the volcanoes of the Andes, and are ejected with streams of mud and
water during eruptions. These fishes may, however, be found in surface
waters at all times, and their appearance in great quantities in the low
country during volcanic eruptions can be accounted for by numbers being
killed by the sulphuretted gases which escape during an eruption and by
their being swept down with the torrents of water issuing from the
volcano. The lowland forms have their body encased in large scutes,
either rough, scale-like, and arranged in four or five series
(_Chaetostomus_), or polished, forming broad rings round the slender and
depressed tail (_Loricaria_, fig. 5). They are mostly of small size.

[Illustration: FIG. 6.--Abdomen of _Aspredo batrachus_, with the ova
attached; at a the ova are removed, to show the spongy structure of the
skin, and the processes filling the interspaces between the ova.]

In certain of the mailed genera the secondary sexual differences may be
very pronounced, and have given rise to many nominal species. The shape
of the snout may differ according to the sex, and its margin may be
beset with tentacles in the male, whilst it frequently happens that the
head of the latter is margined with spines or bristles which are either
absent or considerably shorter in the female.

The _Aspredinidae_, which are also closely related to the _Siluridae_,
are represented by four genera and eighteen species from South America.
_Aspredo batrachus_ (fig. 6), of the Guianas, the largest form, reaching
to about a foot in