142 THE ZOOLOGIST. 



Auchenoglanis biscutatus, a Nile fish, has nine gill-rakers 

 along the first cerato-hypobranchial, seven of them long and 

 upstanding, the other two much smaller, and two on the epi- 

 branchial. Fleshy tubercular gill-rakers grow along the sides 

 of the second and third arches. The upper pharyngeal teeth 

 are in two oval patches, with minute villiform teeth embedded 

 in mucous membrane ; the lower pharyngeals are similar, 



Bagrus bayad, a Nile fish, has thirteen horny gill-rakers on 

 the first branchial arch, with four on its epibranchial. The 

 gill-rakers at the angle of the first arch, of the same length as 

 the depth of the gill lamina below it. The inner sides of the 

 first and second arches are smooth. The outer faces of the 

 second, third, and fourth arches have horny gill-rakers, those on 

 second being longer than those on the other two. The inner 

 faces of the third and fourth arches have small but upstanding 

 gill-rakers. The filter formed by the gill-rakers is not a very 

 close one. The upper pharyngeal teeth, which are villiform, 

 are in two circular shields at the ends of the third and fourth 

 epibranchials. The lower pharyngeal teeth, also villiform, are 

 in two triangular patches close together at their anterior apex, 

 but diverging as they get nearer to the oesophagus. 



Schilbe mystus, a Nile fish, has ten horny gill-rakers on the 

 first cerato-hypobranchial, with three on the epibranchial. The 

 gill-raker at the angle is the same in length as the gill lamina 

 below it is in depth. The other arches carry gill-rakers as 

 described for the last-mentioned fish. The pharyngeal teeth 

 are also similar. 



Callichthys littoralis, the Hassar of Demerara : this is a small 

 fish. On the first and second branchial arches there are soft 

 gill-rakers ; on the third and fourth arches the longer gill-rakers 

 are on the inside of the arch, and fit up against the gill-rakers 

 of the next interior arch, a reversal of the usual plan. There is 

 a large soft pad of mucous membrane, with a row of cardiform 

 teeth below it for the upper pharyngeals. The lower pharyngeal 

 teeth are very minute. 



Platystoma fasciatum has twenty-three fine horny gill-rakers 

 on the first cerato-hypobranchial, with nine on its epibranchial. 

 The longest one at the angle measures four-fifths of the gill 

 lamina below it. The other arches have similar fine hornv 



