THE CIIARACINID^E. Ill 



Loricaria depressa is turned slightly upward. Some species of this genus have been observed 

 lying on the sand fully a yard from the water. 



The genus Aspredo, the type of Dr. Giinther's fourteenth group of Siluroid fishes, is chiefly 

 remarkable for the care which the females take of their young. Dr. Gunther remarks that the whole 

 of the lower surface of the belly, throat, thorax, and a part of the pectoral fins in Aspredo batrachus, 

 shows numerous shallow round impressions to which the ova are often found adhering. The eggs 

 are spread out in a single layer, so as to leave small interspaces between them, which are occupied 

 by short soft appendages to the belly, each of which expands at its free end into a disc, and these 

 bodies help to keep the ova in position. Dr. Gunther thinks it probable that towards spawning time 

 the skin of the lower part of the body becomes spongy, and that after the eggs are deposited, the 

 female lies on them so as to attach them to her body, and that in consequence the spongy substance 

 is absorbed where the eggs press so as to leave the disc-like filaments of the spongy tissue in the 

 interspaces between them. After the eggs are hatched the excrescences disappear and the belly 

 becomes smooth. This genus has no adipose fin, and no strong spine to the short dorsal fin. The 

 anal fin is very long. The gill-opening is a narrow foramen in front of the strong pectoral spine, 

 which is denticulated. The species of this genus are found in British, Dutch, and French Guiana. 

 Some species of the genus Trichomycterus ascend streams in the Andes to an elevation, of fifteen 

 thousand feet. The greater number of the South American Siluroids are small fishes. 



FAMILY II. CHAKACINIDJE. 



The Chai'acinidse are distinguished from the Siluroids by having the head naked, and free from 

 barbels, while the body is covered with scales. The maxillaiy bones form the lateral margins of the 

 upper jaw. The air-bladder is divided transversely into two parts, and is connected with the organ of 

 hearing by auditory ossicles. There are nearly fifty genera in this family, all of which inhabit the 

 fresh waters of tropical Africa and America. In five of the genera allied to Macrodon there is no 

 adipose fin, but in all the other types the adipose fin is present. Some specimens of Macrodon trahira 

 have the tongue smooth, while others show upon it large patches of prickles. The Macrodon aimara, 

 from Cayenne, has very large canine teeth. In the genus Erythrinus the anterior part of the hinder 

 air-bladder has a cellular structure. All the species are from tropical America. The air-bladder 

 presents similar characters in the Lebiasina bimaculata from Peru and Ecuador. The species of the 

 genus Prochilodus which inhabit various parts of South America eat mud, and are remarkable for the 

 great length of the intestine, which is coiled round many times. Great length of the intestine also 

 characterises several other genera in this family, in which the teeth are either absent or extremely 

 small. The nostrils vary in position a good deal in the allied genera, and are commonly 

 more or less distant from each other, but in Tetragonopterus, a tropical American genus, they are 

 close together, and separated only by a valve. In the genus Brycon, which is found in the east of 

 the Ancles, the pre-maxillary bone is armed with three series of teeth, which, like those in the 

 mandible, are notched so as to have three cusps, a character also seen in the genus Chalcinopsis. 

 The lateral line is sometimes absent and sometimes well marked in these fishes ; in the Brazilian 

 genus Gastropelecus it descends obliquely towards the origin of the anal fin. In the Anacyrtus 

 gibbosus the two rows of teeth on the pre-maxillary bone are almost confluent into one. The 

 Anacyrtus microlepis of Brazil has short conical processes like teeth directed outward in both the 

 upper and lower jaws. Some genera, like Xiphostoma, have the snout elongated and conical, the 

 prolongation being formed by a cartilaginous appendage. 



FAMILY III. HAPLOCHITONID^E. 



This family includes two fresh- water genera, which, according to Dr. Gunther, represent the 

 Salmon. Haplochiton, from Tierra del Fuego and the Falkland Islands, has the simple air-bladder 

 united to the thick and muscular stomach. A broad tongue carries a series of curved teeth on each 

 side. The ovaries are in layers, and allow the eggs to fall into the cavity of the abdomen, there being 

 no oviduct. The other genus, Prototroctes, is limited to South Australia. 



FAMILY IV. STERNOPTYCHID^. 



The Sternoptychidse include six genera, four of which are naked, while the other two have 

 the body covered with deciduous scales ; both the maxillary and pre-maxillary bones bear teeth. The 



