12 ON THE GENUS TETRAriONURUS OF RISSO, 



ramus, and on the mandible about forty-four, and are long, 

 slender, compressed and slightly bent backwards at the extreme 

 tip. The vomerine and palatine bones are armed with a distinct 

 row of conical teeth, which are a little curved and strongly inclined 

 backwards from the very hsme, the anterior four or five in each 

 row standing on an appreciably higher level than those succeeding 

 them, while the vomerine row extends rather further back than 

 those on the palatine bones ; along either of the raised edges of 

 the tongue is a row of similar but smaller teeth. 



The dorsal fin commences opposite the middle of the pectoral, 

 and on the thirteenth series of lateral line scales ; the distance 

 between its origin and the tip of the snout being contained three 

 and a quarter times in the total length : the spines are low and 

 somewhat feeble, the longest, which is between the third and 

 sixth, being about two-thirds of the diameter of the eye ; each 

 spine is joined by a delicate membrane to the lower third of its 

 successor, except in the case of the last two or three minute and 

 almost hidden spines which stand alone : the first doi'sal ray rises 

 from the forty-third series of lateral line scales, the last from the 

 fifty-eight, its distance from the root of the caudal being nine-tenths 

 of the length of the head; the rays are delicate, and the highest is 

 but three-fourths of the bo.ly below it. The anal fin commences 

 beneath the fifth dorsal ray, and ends nearer to the caudal than 

 does that fin, so that the distance betweeu its last ray and the 

 base of the caudal is only four-fifths of the length of the head. 

 The ventral fin commences a little behind the base of the i>ectoral, 

 and is very small, its length being about equal to one diameter of 

 the eye. The pectoral fin is placed low down on the side of the 

 body, the upper angle of its base rising at a considerable distance 

 below half the height of the body at that spot, and being but a 

 short distance behind the margin of the opercle, which however 

 it does not touch ; it is pointed and short, from three-fifths to 

 four-sevenths of the length of the head, and about seven and two- 

 fifths in the total length. The caudal fin is deeply forked, and is 

 about one-eighth of the total length the lobes being rounded. The 

 rays of all the fins are exce.ssively fragile. 



