3 3 o Memoir Sears Foundation for Marine Research 



Disc: extreme breadth 51.6, 53.3; length 55.2, 57--- 



Snoui length: in front of orbits 21.8, 22.4; in front of mouth 24.3, 24.3. 



Orbits: horizontal diameter 2.9, 3.3; distance between 2.6, 2.6. 



Spiracles: length i.o, 1.5; distance between 5.1, 5.0. 



Mouth: breadth 4.5, 4.8. 



Nostrils: distance between inner ends 3.8, 4.0. 



Gill openings: lengths, ist 0.75, i.o; 3rd 0.75, i.o; 5th 0.5, 0.6; distance be- 

 tween inner ends, ist 9.2, 10.5; 5th 4.8, 5.6. 



Caudal fin: length of base, upper 6.0, 3.7; lower 5.0, 4.4. 



Pelvics: anterior margin 12.7, 12.2. 



Distance: from tip of snout'" to center of cloaca 47.6, 50.0; from center of 

 cloaca to tip of tail 52.4, 50.0. 



Disc from base of terminal filament about i.i times as long as broad; maximum 

 anterior angle from level of base of terminal expansion of snout to level of spiracles 

 about 85°; end of snout expanded in leaf-like form as shown in Fig. 78 a, terminating 

 in a slender filament a little longer than distance between spiracles; margins of disc 

 rearward from terminal expansion weakly concave or straight about to level of spiracles, 

 then altering to continuously and strongly convex around to short inner margins, with- 

 out definite outer or posterior corners. Tail slender, compressed dorsoventrally, increa- 

 singly so rearward; its width at axils of pelvic fins (where thickest) about 72—^4 ^s 

 great as length of eye; its length from center of cloaca to tip about 1.0- i.i times as 

 great as distance from cloaca to base of terminal filament of snout. 



Skin completely naked everywhere, without dermal denticles of any sort. 



Snout in front of eyes about 8.4—8.7 times as long to base of terminal filament as 

 distance between orbits, its length in front of mouth about 6.0—6.5 times as great as 

 distance between exposed nostrils. Orbit about i.i times as long as distance between 

 orbits, and 2.2—2.9 times as long as spiracle, which is noticeably small. Gill openings 

 minute; first about Ve as long as breadth of mouth; fifth about -/s as long as first; 

 distance between inner ends of first gills about 2.5 times as long as distance between 

 exposed nostrils, between fifth gills about 1.3 times. Nasal curtain conspicuously 

 fringed, each side with 10— 1 1 lobelets; outer margin of nostril only slightly expanded 

 with irregular edge; exposed nostril noticeably minute. Mouth on immature males and 

 on females a little arched forward, its shape not known for mature males. 



Teeth ^|^ on young males, low, with obscure cutting edge but no cusp, but H 

 on largest female, with low, broad triangular cusp, arranged in quincunx. Teeth of 

 mature males not seen. 



No dorsal fins. Base of upper caudal fin-membrane about 1.0— 1.6 times as long as 

 distance between exposed nostrils, of shape illustrated in Fig. 78 a, its maximum width 

 about Vio (about 9 "jo) as great as length of its base; lower caudal membrane about 

 half (55 %) as wide as upper, its origin a little posterior to origin of upper; the two 



30. Exclusive of rostral filament, which is 22 mm long. 



