50 TELEOSTEI : EVENTOGNATHI. — XII. 



epidermis. The fins and other parts are often charged with pig- 

 ment, the usual color being red, but sometimes satiu-white, yellow- 

 ish, or black. 



Note. — Young Cypi'inidcB are usually more slender than adults of the 

 same species, and the eye is always much larger ; thej' also frequently show 

 a black lateral stripe and caudal spot, which the adults may not possess. In 

 the following descriptions, the rudimentary rays of dorsal and anal are not 

 counted. The fins and scales are often, especiallj-in specimens living in small 

 brooks, covered with round black specks, parasitic plants. These should not 

 be mistaken for true color-markings. 



No progress can be made in the study of these fish without careful attention 

 to the teeth, as the genera are largely based on dental characters. The 

 pharyngeal bones in the smaller species can be removed by inserting a pin (or, 

 hetter, a small hook) through the gill opening, under the shoulder girdle. 

 The teeth should be carefully cleaned with a tooth-brush, or, better, a jet of 

 water, and when dry may be examined by any small lens. In most cases a 

 principal row of four or five larger teeth will be found, in front of which is 

 a set of one or two smaller ones. The two sides are usually, but not always, 

 symmetrical. Thus, "teeth 2, 4-6, 1," indicate two rows of teeth on each 

 side, on the one side four in the principal row and two in the lesser, on the 

 other side five in the main row and one in the other. " Teeth 4-4" indi- 

 cates a single row of four on each pharyngeal bone, and so on. 



In the Leucisdne genera, these teeth, or the principal ones, are " rapta- 

 *orial," that is, hooked inward at the tips. A grinding or masticatory surface 

 is an excavated space or groove, usually at the base of the hook. Sometimes 

 the grinding surface is very narrow and confined to one or two teeth. Some- 

 times a bevelled or flattened edge looks so much like a grinding surface as to 

 mislead a superficial observer. In some cases, the edge of the tooth is crenate 

 or serrate. 



Besides the native species here mentioned, representatives of two other 

 genera have been introduced from Europe, and have become inhabitants of 

 some eastern streams. These are Cyprinus Linnaeus, and Carassius Nilsson. 

 The first is distinguished by the very long dorsal, which, like the anal, is pre- 

 ceded by a strong spine, serrated behind. About the mouth are four long 

 barbels, and the teeth are molar, 1, 3-3, 1. This genus is represented by 

 the Carp (Cyprinus caipio L.). The carp is normally covered with large 

 scales. In domestication, however, variations have arisen, prominent ones 

 being the " Leather Carp," naked, and the " Mirror Carp," with a few series 

 of very large scales. 



Carassius Nilsson differs from Cyprinus, chiefly in the absence of barbels, 

 and in having the teeth compressed, 4-4. The Gold-fish (Carassius auratus 

 L.) is originally olivaceous, but only the orange-red variety is valued for 

 aquaria. Both Carassius and Cyprinus are native in China. 



a. Air-bladder surrounded by many convolutions of the very long alimentary 

 canal, which is 6 to 9 times the length of the body. ( Campostomince.) 



b. Teeth 4-4, or 1, 4-4, 0, with oblique grinding surface and slight hook; 



peritoneum black (as usual in herbivorous fishes). Campostoma, 49. 

 aa. Air-bladder wholly above (dorsal) of the alimentary canal. 



c. Alimentary canal elongate, more than twice length of body ; teeth one- 



rowed, the grinding surface well developed, the hook usually slight 

 or wanting; peritoneum usually black. Species chiefly herbivorous. 

 ( Chondrostominm.) 



