SphyroBna barracuda; its Morphology, Habits, and History. 



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pockets or recesses ; a dorsal one as wide as long, and a shallow ventral 

 one lying anterior to the other. The roof of the larger recess is made 

 by the nasals, which are united by and imbedded in a mass of carti- 

 laginous material. The sides of this pocket are formed by two rounded 

 backwardly and slightly inwardly projecting prominences of the maxil- 

 laries. Viewed from above, the anterior ends of the maxillaries, just 

 outside the processes described, are hollowed out into shallow cavities 

 whose use will be described below. Figures 11 and 12, plate iv, show 

 these structures both from below and from above. 



In articulation these bones fit together as follows: the forward pro- 

 longation of the vomer fits into the posterior and dorsally placed cavity 

 between the maxillaries; the backwardly projecting processes of the 

 premaxillaries fit into the spaces between the shoulders of the vomer 

 and the forwardly projecting processes of the palatines; while the united 

 nasals he dorsal to the frontal process of the vomer and between the 

 forwardly projecting horns of the palatines; and lastly the flattened 

 and rounded ventral surfaces of these same horns fit into the grooves 

 excavated into the anterior dorsal surfaces of the maxillaries. Thus 

 there is formed a beautiful joint allowing little motion laterally but 

 considerable in the vertical plane. However, the union of the right 

 and left halves of both maxillaries and premaxillaries by ligaments 

 and cartilage allows a widening of the upper jaw at the angle of the 

 mouth, as will be shown below. 



The rami of the lower jaw are likewise united in front by cartilage 

 and connective tissue, and behind they are hinged onto the quadrates. 

 These in turn are immovably attached by suture joints to the pala- 

 tines. These latter bones are hinged like a door or the lid to a chest, 

 posteriorly to the prefrontals and anteriorly to lateral projections of 

 the vomer. In widening the mouth, the upper and lower jaws spread 

 apart behind and the quadrates and palatines swing outward and 

 upward. This takes place at the same time that the lower jaw drops 

 downward while the tip of the upper jaw is raised. All this results 

 in giving the barracuda an enormous gape, a necessity for a fish 

 which preys on other large fish and which swallows its food in large 

 fragments. These points are well shown in figures 5, plate ii; 7, plate 

 iii; 11, 12, and 13, plate iv. 



The lower jaw is filled with knife- 

 like canine teeth set palisade fashion 

 just inside the hp-like membrane. 

 These are small in front but larger 

 in the middle and posterior parts. 

 They point slightly backward, esj>e- 

 cially those in rear. Their numbers for my five specimens appear 

 in the accompanying table, the dried heads being taken in the 

 ascendmg order of size. The + teeth are the small ones at the 



