PHARYNGEAL TEETH OF FISHES. 141 



for the upper pharyngeal teeth, and similar teeth for the lower 

 pharyngeals. 



Arius proops, from British Guiana, has on the first cerato- 

 hypobranchial ten long horny gill-rakers. There were, however, 

 eleven on the left side first arch. They are about four-fifths of 

 the gill lamina immediately below the longest ones. The first 

 seven from the angle are much of a length, after that they 

 diminish. On the first epibranchial there are five similar ones 

 on each side. There are no gill-rakers on the inner sides of the 

 arches. Those on the outer sides of the second, third, and 

 fourth arches reach across with their points to the inner side of 

 the next outer arch. Those on the third and fourth arches are 

 placed distinctly apart, and as they stretch across to the next 

 outer arch make little square openings for the escape of water 

 to the gills. There are no pharyngeal teeth on the second epi- 

 branchial ; an elliptically shaped shield of villiform teeth grows 

 on the third and fourth epibranchials. The lower pharyngeal 

 teeth, also villiform, are in a long narrow V shape, the two limbs 

 and apex being distinctly apart. 



Arius spixii, from British Guiana, has thirteen horny up- 

 standing gill-rakers, feebly toothed, on the first cerato-hypo- 

 branchial ; the longest of these is just a trifle shorter than the 

 gill lamina below it. On the first epibranchial there are five 

 similar gill-rakers. The inner sides of the other arches have 

 very small outstanding, and the outer sides have upstanding, gill- 

 rakers. A small but distinct patch of ellipsoid shape is attached 

 to the third and fourth epibranchials, covered with minute cardi- 

 form teeth. The lower pharyngeals are on two narrow strips, 

 barely visible in the mucous lining of the floor of the mouth. 



Arius parkeri, from British Guiana, has ten upstanding gill- 

 rakers, about four-fifths of the gill lamina below them in length 

 of the longest, on the first cerato-hypobranchial arch, with four 

 on its epibranchial, and a few rudimentary ones above them. 

 Short upstanding gill-rakers line the outer edges of the other 

 arches, but there are no gill-rakers on the inner faces of any of 

 the arches. An elliptical patch attached to the heads of the 

 third and fourth epibranchials, which patch covered with minute 

 cardiform teeth forms the upper pharyngeals. The lower are in 

 two patches of minute teeth, narrow in shape. 



