55 



The True Sharks 



snout prolonged into a very long and strong flat blade, with 

 a series of strong enameled teeth implanted in sockets along 

 either side of it. These teeth are much larger and much less 

 sharp than in the sawsharks, but they are certainly homolo- 

 gous with these, and the two groups must have a common de- 

 scent, distinct from that of the other rays. Doubtless when 

 taxonomy is a more refined art they will constitute a small 

 suborder together. This character of enameled teeth on the 

 snout would seem of more importance than the position of the 

 gill-openings or even the flattening and expansion of the body. 

 The true teeth in the sawfishes are blunt and close-set, pave- 

 ment-like as befitting a ray. (See Fig. 152.) 



The sawfishes are found chiefly in river-mouths of tropi- 

 cal America and West Africa: Pristis pectinatus in the West 



FIG. 342. Sawfish, Pristis pectinatus Latham. Pensacola, Fla. 



Indies; Pristis zephyreus in western Mexico; and Pristis pecti- 

 natus in the Senegal. They reach a length of ten to twenty feet, 

 and with their saws they make great havoc among the schools 

 of mullets and sardines on which they feed. The stories of 

 their attacks on the whale are without foundation. The writer 

 has never found any of the species in the open sea. They 

 live chiefly in the brackish water of estuaries and river-mouths. 



Fossil teeth of sawfishes occur in abundance in the Eocene. 

 Still older are vertebrae from the Upper Cretaceous at Maes- 

 tricht. In Propristis schweinfurthi the tooth-sockets are 

 not yet calcified. In Sclerorhynchus atavus, from the Upper 

 Cretaceous, the teeth are complex in form, with a "crimped" 

 or stellate base and a sharp, backward-directed enameled crown. 



Rhinobatidae, or Guitar-fishes. The Rhinobatidcs (guitar- 

 fishes) are long-bodied, shovel-nosed rays, with strong tails ; they 

 are ovoviviparous, hatching the eggs within the body. The body, 

 like that of the shark or sawfish, is covered with nearly uniform 

 shagreen. The numerous species abound in all warm seas ; they 

 are olive-gray in color and feed on small animals of the sea- 



