196 Memoir Sears Foundation for Mari?ie Research 



snout is short and obtuse and the midbelt of its disc and the upper surface of its tail 

 are rough with rather large thorns in several irregular rows, the thorns not much larger 

 in any one row than in any of the others. But R. fyllae differs noticeably from the 

 other two species in its longer tail. Young specimens of R. fyllae^ in which there is 

 still only a single row of thorns along the tail, are separable by their longer tails from 

 all other western North Atlantic Skates of similar thorn pattern, with the exceptions 

 of R. bathyphila, R. garmani and young specimens of R. senta. The more obtuse snout 

 oi R. fyllae with its pale lower surface sets it apart from i?. hathyphila, and there is no 

 danger of confusing R. fyllae with R. garmani at any stage in growth, so characteristic 

 is the color pattern of the latter. But the only character we have found to separate 

 newly hatched R. fyllae from newly hatched R. senta (now that the former has been 

 encountered within the range of the latter) is the color of the tail, which is plain- 

 colored in young fyllae but pale cross-barred in young senta. 



Description. Proportional dimensions in per cent of total length. Female, 452 mm 

 long, from Lat. 5i°37' N, Long. 1 1°56' W (British Museum [Natural History]). 



Disc: extreme breadth 49.3; length 40.8. 



Snout length: in front of orbits 9.5; in front of mouth 10.5. 



Orbits: horizontal diameter 4.0; distance between 3.3. 



Spiracles: length 3.1; distance between 6.4. 



Mouth: breadth 5.8. 



Nostrils: distance between inner ends ^.2,. 



Gill openings: lengths, ist 1.3; 3rd 1.3; 5th 1.2; distance between inner ends, 

 1st 12.6; 5th 6.7. 



First dorsal fin: vertical height 2.2; length of base 5.1. 



Second dorsal fin: vertical height 2.0; length of base 6.2. 



Pelvics: anterior margin 10.6. 



Distance: from tip of snout to center of cloaca 39.8; from center of cloaca to 

 1st dorsal 45.7; to tip of tail 60.2; from rear end of 2nd dorsal base to 

 tip of caudal 3.1. 



Interspace between: ist and 2nd dorsals 0.0. 



Disc 1.2 times as broad as long, conspicuously obtuse in front but decreasingly 

 so with growth, the maximum anterior angle in front of spiracles 130—140° in small 

 specimens, 115—125° in adults; tip of snout marked by a low prominence. Anterior 

 margins of pectorals nearly evenly convex in young specimens but weakly concave in 

 larger females and considerably more so in adult males at level of spiracles, some being 

 definitely indented;^ outer corners broadly rounded, posterior margins evenly and 

 moderately convex, posterior corners broadly rounded with curvature extending to axils. 

 Axis of greatest breadth about 70 '/o of distance rearward from tip of snout toward 

 axils of pectorals. Tail with lateral folds confined to posterior one-third and widening 



2. A male of this shape, from Lat. 63° 30' N, Long. 54° 25' W, is pictured by Clark (Rep. Fish. Bd. Scot. [1926], 

 I, 1926: pi. 22, fig. a). 



