354 Memoir Sears Foundation for Marine Research 



Figure 83. Dasyatis centroura, immature male, 1,41 5 mm wide, from Buzzards Bay, Massachusetts (Harv. Mus. 

 Comp. Zool., No. 365 11). A Side view of middle part of tail to slightly larger scale. B Ventral view of pelvic 

 fins. C Tubercle from tail, about 0.8 X. 



Axis of greatest breadth about 47 "/o of distance rearward from tip of snout toward 

 rear limit of disc. Tail from center of cloaca about 2.4—2.6 times as long as distance 

 from center of cloaca to tip of snout; moderately depressed anterior to spine on small 

 specimens but not appreciably so on larger; oval close posterior to spine but altering 

 to rounded wedge-shaped in cross section (widest above) toward tip; its upper surface 

 with a low ridge under tip of spine, rounded thence rearward; its lower surface with 

 a well developed cutaneous fold extending rearward from below origin of spine for a 



