290 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



a'. ToKPEDOiDEi. Disk broadly rounded ; snout short, obtuse ; teeth raptorial, 

 small, in bands ; nasoral grooves present ; well developed electric organs ; 

 pelvis arched backward, with lateral prepelvic extensions ; tail short, with 



2 dorsals, 1 dorsal or none and well developed caudal Torpedinidae 



a'. Rajoidei. Disk broad, angular to rounded ; skull extended in narrow pointed 

 rostral cartilage, rarely obsolete; teeth small, in pavement; nasoral grooves 

 present ; electric organs rudimentary or absent ; pelvis transverse with 

 lateral prepelvic extensions ; tail moderate to slender, usually with 2 small 



dorsals and more or less imperfect membranous caudal Rajidae 



a*. Myliobatoidel. Disk broad to greatly so, polygonal to rounded ; pelvis arched 



forward, with median prepelvic extension; tail slender, whiplike, without 



or with 1 to 3 serrated spines, rarely rayed fins present, sometimes only as 



low membranes. 



c\ Teeth small, in pavement ; pectorals form broad rounded to polygonal disk 



and usually obtusely pointed snout Dasyatidae 



c". Teeth broad, molarial ; snout usually in single lobe, sometimes divided ; 



pectorals form broad polygonal disk, angular Myliobatidae 



(f. Teeth minute, very numerous in bands ; snout very wide, with 2 lateral 

 lobes ; pectorals and body very wide, massive, angular, disk 

 polygonal Mobulidae 



Family PRISTIDAE 



Body elongate, robust, moderately depressed, flattened below. Fold 

 along each side of tail. Snout extended in long, thin, flattened blade, 

 each side of which with row of strong toothlike points set in sockets. 

 Eye without nictitating membrane. Teeth in jaws obtuse, very small 

 and numerous. Nostrils inferior. No tentacle. Spiracles rather 

 large. Dorsals large, without spines, first nearly opposite or above 

 ventrals. Caudal well developed, bent up, usually with lower or sub- 

 caudal lobe. Pectorals moderate, front edge quite free, not reaching 

 snout. 



One genus. Large fishes of tropical and subtropical seas. They 

 often ascend tidal rivers. Living on the bottom the large sawlike 

 rostrum is said to be used in raking or rooting up the sand and thus 

 make available their food, which consists largely of various marine 

 animals living on or near the sea bottom. Stories of sawfishes attack- 

 ing large marine animals and cutting out portions of their flesh by 

 blows of the saw are doubtful. The saws are, however, dangerous 

 weapons and capable of causing serious lacerations to the incautious. 

 The young are produced alive. Several fossils, as Sclerorhynchus 

 from the Chalk of Mount Lebanon and PropHstis from the Upper 

 Eocene beds of Egypt, are interesting. The former, with more super- 

 ficially placed rostral teeth without sockets in the rostral cartilages, 

 suggests a closer approach to the usual dermal spines in the genus 

 than any of the recent sawfishes. In PropHstis the rostral teeth are 

 also without sockets. 



