3 5^ Memoir Sears Foundation for Marine Research 



arid finely fringed, the individual lobelets single or bifid with rounded tips. Mouth 

 weakly arched on females and on immature males, its shape on fully mature males not 

 known. Floor of mouth with a transverse row of about six fleshy papillae of different 

 lengths. 



Teeth of females and of immature males closely crowded in quincunx; tetragonal 

 with rounded corners, the functional surface more or less flattened, without cusp and 



Figure 84. Dasyatis centroura. A Opened mouth of female, about 1,330 mm wide, from Woods Hole, Massa- 

 chusetts (Harv. Mus. Comp. ZooL, No. 36513) to show tooth bands, transverse curtain on roof of mouth, and 

 papillae on floor of mouth, about 0.6 X . B Upper teeth of same from near middle of jaw, about 5.2 X. C Nostrils 

 and mouth of male pictured in Fig. 83, about 1.2 X . D Tip of tail spine. E Middle part of spine. F Cross section 

 of middle part of spine of same, about 5.8 X. 



variously grooved with wear; about seven rows in function simultaneously in center 

 of upper jaw, about 12—14 rows in center of lower jaw, progressively fewer rows in 

 function toward corners. Teeth of mature males not seen. 



Pelvics quadrate; anterior and distal margins nearly straight or only weakly con- 

 vex, the inner margins a little more strongly so; outer corners abruptly rounded, 

 posterior corners more broadly so; anterior margin about 75—80 "/o as long as distance 

 from its own origin to rear tip of longest ray of pelvic. 



Color. Described as olive-brown above, white or nearly so below. Fresh-caught 



