sucks its fill of blood. A special secretion from buccal or mouth glands keeps 

 the blood from clotting until the lamprey has finished its meal — a development 

 also found in the blood-sucking leeches. Once satisfied, the lamprey leaves its 

 host, attaches itself to a rock and digests its meal before it again attacks a fish. 

 The sea lampreys swim up the rivers to spawn in fresh water. Some of the 

 lampreys develop spectacular orange coloring at spawning time, but this is not 

 constant, as some dark and some brightly colored individuals may be seen in 

 the same run, and some years very few colored ones are to be found. It seems 

 probable that none of the adults of any species survive the spawning period, as 

 the digestive tract is almost completely degenerated and there is no trace of 

 any second crop of eggs. It is possible to collect larval lampreys from suitable 

 gravel bars in lakes or rivers, by means of a wire strainer, and those about to 

 transform will live for some time in a shaded aquarium. 



One group of fishes appeals to the layman because of its peculiarities and 

 to the scientist because of the light it throws on taxonomic and evolutionary 

 problems. The species of this group have heterocercal tails and a number of 

 internal anatomical pecularities which place them as primitive fishes, inter' 

 mediate between sharks and the true bony fishes. Here we find the gars, 

 widely distributed fishes with long, almost cylindrical bodies and peculiar, dia' 

 mond'shaped scales, so hard as to lead the pioneer naturalist, Rafinesque, to 

 state that they would turn a musket ball. A long mouth, resembling a duck's 

 or a heron's beak but full of needle-like teeth, completes the pirate's make-up. 

 Another odd fish is known, because of its huge spatulate snout, as the paddlefish 

 or spoon-bill. This species was formerly very common, and is still fairly abund- 

 ant, in the Mississippi River and its larger tributaries. It has an inferior mouth 

 like that of a shark, soft flaps for gill covers, and no evident scales. Although 

 it may reach a length of six feet and a weight of one hundred and fifty pounds, 

 it lives almost entirely on microscopic organisms, and is supposed to use its huge 

 paddle as a spoon to stir up and concentrate these minute morsels. A very 

 similar fish, probably its only living near relative, is found in the Yangtse River 

 in China. A third division of this group of primitive fishes contains the stur- 

 geons, which have reduced the number of their scales and fused some to form 

 huge, bony dermal plates. These plates usually lie in rows on each side, so that 

 protection is obtained without the sacrifice of flexibility. As the sturgeon ma- 

 tures, it often loses these bony shields. Some species become five or six feet 

 long. Mature female sturgeons are highly prized for the roe, which is known 

 as caviar when properly prepared. The roe of the paddlefish also makes good 

 caviar, but that of the gar, strangely enough, is reported to be toxic. These 

 fishes — gars, paddlefish and sturgeons, together with the bowfin or river dogfish 

 — are often referred to as the Ganoids, although only the gars have well de- 

 veloped ganoid scales. They are the survivors of a once very numerous group, 

 well represented in fossil beds. 



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