30 NEW SOUTH WALES 
CHAPTER ITI. 
Our Marine Food Fishes. 
Tue study of fishes, were it only in an economical point of view, is of 
the greatest importance and interest. As articles of food, though but 
one of the uses of fishes, they must even command our attention, yet 
their value in this respect is hardly appreciated. Fish is known to bea 
light and easily digested diet, but it is not known that it contains as 
much proteim as pork, and.consequently 100 Ibs. of fish contains as much 
nourishment as 200 Ibs. of wheaten bread and 700 Ibs. of potatoes, This 
encouraging fact may well awaken our interest sufficiently to enable us 
to get over the following dry technicalities which are a necessary key to 
the comprehension of the subject. 
It will be borne in mind that fishes are divided into four sub-classes, 
viz. :—Teleostei, Paleichthyes, Cyclostomata, and Leptocardii. Each of 
these sub-classes are divided into orders and sub-orders. Each of the 
orders are separated into divisions, and these again into families. The 
families are made up of similar genera, and the genera comprise one or 
more distinct species. It is very difficult for the mind to grasp these 
distinctions at once, because their number becomes so'bewildering. It 
will facilitate the comprehension of these methods if we suppose the 
class fishes to represent a kingdom ; the sub-classes, the counties; the 
divisions, the parishes ; the families, the villages or towns; the genera, 
the houses ; and the residents, the species. 
Sub-class TELEOSTEI. 
Heart with a non-contractile arterial bulb, optic nerves crossing, intes- 
tine without spiral valve, skeleton bony, vertebrae completely formed, tail 
generally homocercal. 
This sub-class is divided into six orders :— 
1, Acanthopterygii.—Part of the rays of the dorsal, anal, and ventral 
fins composed of non-articulated spines. The lower pharyngeal bones 
separate. The air-bladder in the adult without a pneumatic duct. 
2. Acanthopterygii pharyngognatht.—The same features as the last, 
but the pharyngeal bones united, 
3. Anacanthint.—Vertical and ventral fins without spinous rays. 
Ventral fins (if present) jugular or thoracic. Air-bladder (if present) 
without pneumatic duct, lower pharyngeal separate. 
4. Physostomi.—All the fin rays articulated ; only the first of the 
dorsal and pectoral fins is sometimes ossified. Ventral fins if (present) 
oe and without spine. Air-bladder (if present) with a pneumatic 
uct, 
5. Lophobranchit.—Gills not laminated, but composed of small 
rounded lobes attached to the branchial arches. Gill cover reduced to 
a large simple plate. A dermal skeleton replaces the more or less soft 
integuments. 
