428 



FISHES. 



true that tlie sounds are accompanied by a tremulous motion 



of the vessel, it seems more pro- 

 bable that they are produced l)y 

 the fishes beating their tails 

 against the bottom of the vessel 

 in order to get rid of the para- 

 sites with which that part of 

 their l)ody is infested. The 

 " Drum " attains to a length of 

 more than four feet, and to a 

 weight exceeding a hundred lbs. 

 Its air-bladder has l:)een figured 

 on p. 146. 



Micropo(jon is closely allied to 

 Pofioni(is,\y\\t has conical pharyn- 

 geal teeth. Two species from the 

 western parts of the Atlantic. 



Fig. 187. — Pluiryugeal hones and 



teetli of Pogonias chroviis. 

 A, Upper ; B, Lower pharyngeals. 



Umbrina. — Snout convex, Avith the upper jaw overlapping 

 the lower ; a short barbel under the symphysis of the mandible. 

 The first dorsal with nine or ten flexible spines, the anal with 

 one or two. Scales of moderate size. 



Fig. 188. — Umbrina nasns, from Panama. 



Twenty species are known from the Mediterranean, 



