512 Memoir Sears Foundation for Marine Research 



dorsal and caudal. Caudal only about Vr the total length, about % as broad as long, the tip 

 broadly rounded, its posterior outline deeply concave in angular contour, marking off the 

 terminal sector, the lower lobe broadly triangular with narrowly rounded tip, its anterior 

 margin about % as long as upper margin of fin. Pectoral about % (40-45%) as long as 

 head to 5th gill opening. 



Color. Dark brown above, paler brown or brownish white below, except for a con- 

 spicuous dark collar around the neck in the region of the gill openings; fins brown, the 

 pectorals, dorsals and pelvics with pale distal margins, the upper and lower lobes of the 

 caudal with dusky or darker brown tips; the inner side of upper eyelid not pigmented. Ex- 

 cept in the region of the dark collar the lower surface is closely, and the sides sparsely, 

 sprinkled with black dots, presumably luminous ;'' these also occur in patches on the sides 

 of the head, on the dorsal and caudal fins, and on the basal parts of the pectorals, with a few 

 along the back. 



Size. Recorded specimens have ranged in length from about 140 mm. (5% inches) 

 to about 495 mm. (19V2 inches); females are mature at a length of 18 inches. 



Developmental Stages. Presumably development is ovoviviparous, but the only 

 available definite information is that a female has been reported as containing six large 

 eggs.' 



Habits. This is a pelagic species, the majority of recorded specimens having been 

 taken either from small depths or at the surface at night. And while a few have been re- 

 corded from deep hauls,* it is likely that they were picked up by the net on its way down 

 or up. Nothing is known of its diet, nor of its breeding habits. 



This is the most brilliantly luminescent of sharks. According to an eyewitness 

 account'' the entire lower surface of its trunk, with the exception of the dark collar, its 

 paired fins and its caudal, emits a vivid greenish light. While the luminescence apparently 

 is not under nervous control, since it is not affected by handling, it is not a constant charac- 

 teristic of the species, for one specimen taken alive failed to show any trace of it." 



Range. The localities of capture include the Gulf of Guinea, the offings of Sierra 

 Leone and Cape Verde in the eastern Atlantic, as well as Brazil, the Bahamas, and north 

 of the Bahamas in the western Atlantic; also the vicinity of the Galapagos, Hawaiian Is- 

 lands, Japan, Fiji, central equatorial Pacific west of Christmas Island, equatorial belt 

 north of New Guinea, Lord Howe Island off New South Wales, Australia, Mauritius, 

 and between Java and western Australia. These localities are dispersed widely enough to 

 prove this shark cosmopolitan in the tropical and subtropical belts of all three oceans. Rec- 

 ords for the western Atlantic are: off Rio de Janeiro (one specimen), among the Bahamas 



z. The distribution of these has been described in detail by Burckhardt (Ann. Mag. nat. Hist., [7] 6, 1900:565, 566). 



3. Bennett, Narr. Whaling Voy., j, 184.0: 255. 



4. See Study IVIaterial, p. 509; also Garman (Mem. Harv. Mus. comp. Zool., 34, 1899; 40) and Parr (Bull. 

 Bingham oceanogr. Coll., 3 [7], 1937: i). 



5. F. D. Bennett's (Narr. Whaling Voy., 2, 1840: 255) account has been quoted repeatedly. 



6. Duncker and Mohr, Mitt. zool. Stinst. Hamburg, ^j, 1929: 84. 



