THE PHARYNGEAL TEETH OF FISHES. 73 



branchial arch, and they carry teeth ; four are placed on top of 

 the outer margin and the other six, likewise on top, but inclined 

 towards the inner margin. The other arches are provided with 

 similar gill-rakers. As for providing a filter to the water 

 passing into the gills, they seem inadequate for the purpose. The 

 upper pharyngeal teeth consist of a long, narrow strip on the 

 second epibranchial; a small group on the heads of the third 

 and fourth epibranchials with two rows of stout cardiform 

 teeth, and a thin narrow line of smaller cardiform teeth on the 

 limb of the third epibranchial. The lower pharyngeal teeth 

 are arranged in two groups forming a crescent well advanced 

 from the oesophagus and having a broad division between them 

 in the middle. 



Z0ARCID.ffi. 



Zoarces viviparus (the Viviparous Blenny), in the specimen 

 examined, had nine small gill-rakers on the right side, and eleven 

 on the left side on the cerato-hypo portion of the first branchial 

 arch, those in the central position being upstanding ; they 

 become more diminutive as they get further forward. The other 

 branchial arches carry gill-rakers that fit in alternately and make 

 an efficient filter. The upper pharyngeal teeth consist in their 

 upper portion of a row of small but strong conical teeth set close 

 together, then a dividing strip of mucous membrane and more 

 conical teeth, but not as long as the upper ones. The lower 

 pharyngeal teeth consist of two groups of conical teeth meeting 

 in the central line of the mouth, but with a well-defined line of 

 separation, the teeth in each group set in two rows, the inner 

 rows being the stronger. 



(To be continued.) 



Zool, Idle ser. vol. XX., February, 1916, 



