140 THE ZOOLOGIST. 



pharyngeals are in two long patches of minute teeth, with a 

 stronger row on each of the inner margins. The basibranchials 

 also are covered with minute teeth. All the teeth in the gullet, 

 minute as they are, offer considerable resistance to the feel if a 

 finger is drawn over them against the direction of the swallow. 



Myletes setiger, the Pacu of British Guiana, has nineteen 

 short, horny gill-rakers on the first cerato-hypobranchial, and 

 sixteen on the epibranchial ; they are non-denticulated. The 

 longest — the first few near the angle — are about one-third the 

 depth of the gill lamina below them. The other arches bear 

 shorter but numerous gill-rakers on each side, making a very 

 good filter. The gill-slits run very far into the fissures covering 

 the basibranchials, leaving but a very narrow slip in the middle 

 line between the slits on each side ; some minute teeth on the 

 upper part of the second and third epibranchials represent the 

 upper pharyngeal teeth, and some similar teeth at the back of 

 the mouth on the fifth branchial arch represent the lower 

 pharyngeal teeth. 



Myletes ellipticus has fifteen moderately long, horny gill- 

 rakers on the first cerato-hypobranchial arch, the longest about 

 one-half the depth of the gill lamina below it ; they are not 

 denticulated. The other arches carry numerous small gill-rakers 

 on each side, making a good filter. The gill slits in this fish do 

 not run up so closely to each other on opposite side as in 

 M. setiger. The pharyngeal teeth are minute and similarly 

 placed as in the last-mentioned fish. 



SlLURIDiE. 



In this family the teeth visible in the jaws and front of the 

 mouth are feeble, especially when compared with those of the 

 ( 'haracinidce, but their pharyngeal teeth are more effective. 



Bagarius yarrelli is, however, an exception ; its visible teeth 

 in both upper and lower jaws are long and pointed, its upper 

 pharyngeal teeth are strong and cardiform, and resemble minia- 

 ture tiger claws ; they were referred to in the opening article of 

 this series.* 



/Elurichthys gronovi, from Demerara, has cardiform teeth 



* ' Zoologist,' November, 1910, p. 418. 



