62 Memoir Sears Foundation for Marine Research 



Distinctive Characters. The peculiar shape of the disc and the long wedge-shaped 

 snout, combined with the stout muscular tail and its two well developed dorsal fins, 

 mark Rhinobatos lentiginosus off from all other batoids of the western Atlantic except 

 its genus mates R. percellens and R. horkelii (see discussion, p. ^■;^'). The spatulate rostral 

 cartilage of R. lentiginosus, its relatively shorter nostrils, and the fact that the tubercles 

 along the midline of its back are smaller and less thorn-like in shape, set it apart from 

 R. horkelii \ so too, the pale-spotted color pattern of specimens that are marked in that 

 way. Its tubercle-tipped snout and more broadly spatulate rostral cartilage differentiate 

 it from R. percellens, while the color pattern differs in detail between such specimens 

 of lentiginosus and percellens as are marked with pale spots (p. 68). 



Description. Proportional dimensions in per cent of total length. Male, 508 mm, 

 from Captiva Pass, Florida (Harv. Mus. Comp. Zool., No. 35857). Female, 577 mm, 

 from Pine Island, Florida (Harv. Mus. Comp. Zool., No. 35856). 



Disc: extreme breadth 29.9, 33.0; length 39.0, 41.7. 



Snout length: in front of orbits 14.2, 14.0; in front of mouth 17.3, 17.3. 



Orbits: horizontal diameter 2,-Si 3*4' distance between 3.1, 2.9. 



Spiracles: length 2.0, 2.0; distance between 5.1, 5.2. 



Mouth: breadth 6.4, 6.2. 



Nostrils: length 3.8, 3.6; distance between inner ends 3.3, 3.1. 



Gill openings : lengths, ist 1.3, 1.2; 3rd 1.4, 1.5; 5th i.o, i.o; distance between 

 inner ends, ist 12.4, 12.7; 5th 8.2, 9.0. 



First dorsal fin: vertical height 6.3, 6.4; length of base 4.8, 4.5. 



Second dorsal fin: vertical height 6.6, 6.5; length of base 5.3, 4.9. 



Caudal fin: upper anterior margin 14.9, 13.5. 



Pelvics: origin to tip 16.5, 15.2. 



Distance: from tip of snout to center of cloaca 41.3, 45.2; from center of cloaca 

 to tip of tail 58.7, 54.8; from tip of snout to ist dorsal 59.3, 60.7. 



Interspace between: ist and 2nd dorsals 1 1.2, 10. o; 2nd dorsal and caudal 5.9, 5.9. 



Disc about V4~V6 ^^ broad as long to posterior limits of pectorals; wedge-shaped 

 anteriorly but with well rounded tip, its angle in front of orbits about 50° ; posterior 

 corners well rounded; anterolateral contours nearly straight in young specimens but 

 slightly concave anterior to the level of eyes in large; posterior margins evenly and 

 moderately convex; posterior corners of pectorals overlapping pelvics by a distance 

 about as long as that between nostrils. Tail from center of cloaca 1.2— 1.4 times as 

 long as distance from snout to cloaca, nearly flat below, moderately rounded above, 

 tapering evenly rearward, its breadth opposite axils of pelvics about twice as great as 

 distance between spiracles; its lateral dermal folds originating opposite tips of pelvics 

 and extending to lower origin of caudal, their width opposite interspace between dorsals 

 (where widest) about Ys ^s great as horizontal length of eye. 



Dermal denticles on upper surface minute and close-set, but skin exposed between 

 them; low, flattish or slightly domed; those along midzone of back ovate posteriorly, 



