338 Memoir Sears Foundation for Marine Research 



jecting fold which is expanded when the water is agitated, thus protecting the spiracular 

 opening from sand, etc. Normally, however, the spiracles are open in respiration for 

 the intake of water, which is expelled via the gill openings, as in the case of Skates." 



Though lying quiescent for a large proportion of the time. Sting Rays are active 

 swimmers on occasion, progressing rapidly by undulating motions of the margins of 

 the pectorals much as Skates do. When on migration, or at other times for reasons 

 not evident, they swim at the surface or plane along the latter. 



Numerical Abundance. We have found no precise information as to the numerical 

 abundance of Sting Rays anywhere. It is common knowledge, however, that in suitable 

 localities in tropical coastwise waters they occur in such great plenty that it may seem 

 as though the bottom were almost paved with them. 



Relation to Man. Sting Rays of one sort or another are often offered for sale in 

 the fish markets of tropical ports, the thicker parts of their discs alone being utilized. 

 Their fins are used to some extent for gelatine and their liver-oil "is scarcely distin- 

 guishable in appearance or composition from cod-liver oil,"i^ but we are not aware 

 that its vitamin content has been measured. 



The spines of Sting Rays are such effective weapons that their use for tipping 

 spears, either singly or several bundled together, was once fairly common practice in 

 the Malay-Siam region, in New Zealand, among the island groups of the tropical and 

 subtropical Pacific, and in Central and South America; in fact, they are still used by 

 the aborigines of northern Australia.^* In the Carolines they were used on daggers." 

 They have been used also as needles or as awls. In Central America, at localities well 

 inland, they have been found in burial sites in numbers so great as to suggest that they 

 were a regular article of trade." In Malaya, too, they have been employed as a poison," 

 and along the Congo in tropical West Africa whips were made from the thorny tails 

 of an African Sting Ray, and perhaps they still are.^" Pieces of the spiny skins of Rays 

 (genus Urogymnus), sewed with coconut fibre around sticks of wood 6-10 inches long, 

 were used by the natives of the Gilbert group "so to shape the boards of their canoes 

 that when sewed together they were watertight;"-' however, this practice has now been 

 replaced by the use of steel rasps. The skins of other smoother Rays have been em- 

 ployed for drum heads. On the debit side, Rays do more or less damage to cultivated 

 oysters in Cavite Bay, Luzon, Philippines; at high tide they swim over the bamboo 

 stakes that surround the beds and crack "open the oysters so that only halves of oyster 

 shells cemented to the stakes remain. "^2 And the inroads that they make on the local 

 shellfish beds elsewhere must be great in regions where they are abundant. Also, they 



14. Raj, Rec. Indian Mus., jo, 1914: 317. 15- Donovan, Trans. Proc. N. Z. Inst., 52, 1920: 29. 



16. See Whitley (Fish. Aust., i, 1940: 193, fig. 222) for distribution of Australian Sting Ray spears. 



17. The late Sir P. H. Buck informed us that there is a dagger from the Carolines, with two Sting Ray spines, in the 

 Bishop Museum, Honolulu, T. H. 



18. Lothrop, Peabody Mus. Mem., 7, 1937: 97-98; Merwin and Vaillant, Peabody Mus. Mem., 3, 1932: 90; Kidder, 

 Amer. Antiquities, 2 (2), 1945: 68, footnote. 



19. Gimlette, Malay Poisons, ed. 1923: 117. 20. Whitley, Fish. Aust., i, 1940: 194. 



21. See Walcott (Occ. Pap. Bishop Mus. Honolulu, i [2], 1900; 32) for description and photographs. 



22. Villadolid and Villaluz, Philipp. J. Sci., 67, 1938: 394. 



