are placed in one container, each may be wrapped in cheesecloth and another 

 label tied to each bundle. Colors bleach out under any condition, but more 

 rapidly if the specimens are exposed to light or preserved in alcohol. Im' 

 properly cared for specimens which have dried up can be partially restored 

 by soaking them in 2% solution of potassium hydroxide, but close watch must 

 be kept or they will disintegrate or become transparent. They should be 

 thoroughly washed before they are returned to a preservative. 



Measurements 



Fishermen usually consider the length as the over'all measurement. The 

 scientist measures from the tip of the nose to the root of the tail, the fin portion 

 of the tail not being included. The depth or height is the next most common 

 measurement, being the greatest vertical distance from dorsal — usually the base 

 of the dorsal fin — to the ventral side. These measuremicnts are often expressed 

 as proportions. Thus we might say that the black bass has its depth 3 in length 

 and some of the darters have depth 6 or more in length. The length of the 

 head, from the tip of snout to the back of the stiff part of the operculum, is 

 another useful measurement. The snout is measured from the tip of the head 

 to the front of the eye. Always take actual measurements. Markings and 

 structures create optical illusions, and an estimate is seldom reliable. 



The Tail 



The ganoid group of fishes has an asymmetrical and primitive type of tail, 

 resembling that of sharks. The vertebral column extends at least slightly into 

 the upper lobe of the tail fin, a condition called heterocercal. 



Most of the bony fishes have a superficially symmetrical tail, the homO' 

 cereal, the end of the backbone being formed by a large bone called the uro' 

 style. Actually, as Louis Agassi^ pointed out, this is an extreme development 

 of the heterocercal tail, the end of the vertebral column being turned still 

 further upward, the upper lobe of the tail fin disappearing and the lower lobe 

 spreading to form the apparently complete symmetrical one. This process is 

 recapitulated in the early development of many teleosts. In the Cod family, 

 (Gadidae), a truly symmetrical tail known as isocercal has been developed 

 through the loss of the original one and the meeting of parts of the dorsal and 

 anal fins. 



The Fins 



The fins fall into tVv'O categories: the unpaired, consisting of the dorsal and 

 anal; and the paired, which correspond in a general way to the limbs of higher 

 animals. In the more primitive fishes the fins are supported only by rays — soft, 

 segmented, and more or less branched structures. More specialized fishes have 

 also unsegmented and unbranched spines. In technical descriptions the spines 

 are referred to by Roman numerals, the rays by Arabic, so to an ichthyologist 



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