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Memoir Sears Foundation for Marine Research 



Midline of back with a row of ridge-like tubercles, truncate posteriorly, on smooth 

 oval bases; partly-grown specimens (375—425 mm wide) with about eight of these 

 from nuchal region rearward, followed next by a considerable gap, then by two or three 

 tubercles close in front of tail or on its base; mature specimens with the median row 

 numbering 30 or more,*' continuous or nearly so though irregularly spaced; each 

 shoulder also developing a longitudinal series of smaller tubercles, from 2—3 at first 



Figure 82. Dasyatis americana. A Nostrils, nasal curtain and mouth of male pictured in Fig. Si. B Detail of 

 margin of nasal curtain from right-hand side, about 1.3 X. C Detail of margin of nasal curtain from left-hand 

 side, about 1.3 X. D Left-hand half of upper tooth band, about 3.3 X. E Right-hand half of upper tooth band 

 of female, 448 mm long, from Rio de Janeiro, Brazil (Harv. Mus. Comp. ZooL, No. 571), about 3-3 X. 



to 10—12 at maturity; both medians and scapulars larger and more conspicuous on 

 females than on males; areas between orbits and between spiracles sparsely prickly on 

 males by maturity, more densely so on females, also prickly on nuchal and scapular 

 regions; a belt along either side of the median row of tubercles more or less prickly 

 on medium-sized specimens (about 40 in. wide), the largest (about 60 in. wide) with 

 prickles covering entire disc; upper and lateral surfaces of tail close in front of spine 

 and posterior to it rough with prickles on large specimens, but smooth farther forward; 

 pelvics smooth in both sexes. Lower surface smooth on disc and on tail anterior to spine. 

 Snout in front of orbits about as long as distance between outer edges of orbits, 

 its length in front of mouth 1.8-2.0 times as great as distance between exposed nostrils 



47. Sixty have been reported for a Cuban specimen (1,058 mm wide) that may have been of this species, by Fowler 

 (Fish Culturist, 21, 1942: 66 as "Dasyatis scabrata"); see also p. 352, footnote 64. 



