SYNOPSIS OF THE CYPRINIMI OP PENNSYLVANIA.. 



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active, and with the sluggish Exoglossa and Campostomae, glide in short gyrations in the 

 depths of the clear and quiet pools of our forest streams. The Stilbe and Hypsilepis cor- 

 nutus, with some Hybopscs, do not dread the neighborhood of mankind ; they are the deni- 

 zens of the milldam and race, and are usually the chief ornaments of the " strings" of the 

 urchins, whose wanderings have not attained the river or creek bank. They are equally 

 abundant in the quiet parts of the large rivers, where their dimensions are quite dignified 

 in comparison with the swarming Hypsilepcs, Alburnelli, Hybopses, and Hyborhynchi, 

 whicli prefer the same localities. 



These differences of habit are associated with peculiarities of food and of the structure 

 of the digestive system. Few families of vertebrates embrace as great a variety in these 

 respects as the present one. There arc carnivorous, insectivorous, and graminivorous gen- 

 era, which arc distinguished as among mammalia, the former by the abbreviation, the last 

 by the elongation, of the alimentary canal ; in the former the teeth are usually sharp- 

 edged or hooked, in the latter truncate, hammer, or spoon-shaped. John Jacob Heckel, 

 however, the author who has developed the characters of the Cyprinidoe more than any 

 other, says in reference to tins point : " It is known that in general the length of the ali- 

 mentary canal, as well as the direction of the oral opening, corresponds to the manner of 

 nourishment of the animal, but among our Cyprinidse this rule lias but a narrow applica- 

 tion, since the common carp (Cyprinus carpio), whose alimentary canal is only double the 

 length of the whole body, is as completely herbivorous as those East Indian species whose 

 intestines arc wound knot-like in a, length of eleven times that of the body. On the con- 

 trary, the species of BarbUs, whose alimentary canal is similar in length to that of Cypri- 

 nus, or our Rhodeus, the only European which resembles the Indian species in the length 

 and involution of its intestines, live altogether on animals." 



In the American genera, as far as included in the scope of this essay, the peculiarities 

 of the intestines correspond with the food. In the Alburnellus rubrifrons, they are but * 

 the length of head and body (excluding caudal fin). In Hypsilepis kentukiensis, Pho- 

 togenis leucops, Argyrcus atronasus and nasutus, Ericymba buccata, and Exoglossum 

 maxillingua, abut I ; the food of the last five species is insects and crustaceans, the last 

 depending largely on mollusca. In the species of Ccratichthys, Semotilus, and Hybop- 

 sis, with Hypsilepis cornutus, ];:, to equal the length; the habits, insectivorous. The 

 genera with longer intestines are, first, Stilbe 1| to 1| the length; Chrosomus, Hyborhyn- 

 chus, and Pimephales 2§ to 2|, and Hybognathus 4 times. The intestines in these are 

 generally filled with a soft dark-colored slime, without remains of insects, but of vegetable 

 origin. In the remarkable genus Campostoma the canal extends to between eight and 

 nine times the length, and, like that of other vegetable-feeders, is usually found occu- 

 pied by the ingesta for a considerable part of its length. The European genera most 

 vor>. xni. — +5 



