1 1 o Memoir Sears Foundation for Marine Research 



ascldians, amphipods, small shrimps, and other Crustacea. i" Their feeding habits have 

 not been observed, but their known diet and the structure of their jaws and lips suggest 

 that they suck into their protruded mouths whatever soft-bodied animals they may 

 encounter on bottom (or close to it), rather than that they pursue more actively swim- 

 ming prey. 



The electric shocks of Narcine are much weaker than those of Torpedo, the highest 

 recorded voltage being about 37, and apparently a more active stimulus is required to 

 induce the former to discharge."^ 



Relation to Man. These little Electric Rays, though locally common, have never 

 been of any commercial importance. 



Range. Continental waters of the western Atlantic from N. Carolina and Texas 

 to southern Argentina; Pacific Coast of America from the Gulf of California to Pa- 

 nama; Indo-China, China and Japan; Malaysia and East Indies; southeastern and 

 southern Australia (Queensland and Victoria) and Tasmania; India. There is no re- 

 liable report of the presence of Narcine anywhere in the eastern side of the Atlantic, 

 in the Red Sea, or along the African Coast of the Indian Ocean,!-" unless the limits 

 of the genus be expanded to include the species that are classed here (p. 89) as 

 Heteronarce.^'^^ 



Species. Examination of representatives of five of the species concerned ^-^ from 

 widely separated localities leads to the conclusion that the most useful characters for 

 purposes of specific identification are: (a) distance between eyes and spiracles; (b) shape 

 of caudal; (c) margins of spiracles smooth or corrugated; (d) shape of joint anterior 

 nasal curtain; (e) shape of pelvics; and (f) color in the case of the more conspicuously 

 marked species. The position of the origin of the first dorsal relative to the axils of 

 the pelvics is useful only if the question of sex be taken into account, since males and 

 females differ in this respect. But final diagnoses must await first-hand comparisons 

 between adequate series of the Malaysian species, including a final decision as to 

 whether the Raja maculata of Shaw i 804^^^ was an earlier name for Narcine indica Henle 

 1834 or a later name for N. timlei Bloch and Schneider 1801. 



118. Stomach contents have been recorded by Beebe and Tee-Van (Zoologica N.Y., 26, 1941: zi^j) iov N. enlemedor, 

 and by Richardson (Trans, zool. Soc. Lond., 3, 1844: 182) for N. iasmaniensis. For stomach contents oi N. brasili- 

 ensis, see p. 119. 



119. This reluctance, reported by Annandale for the Indian' A^. timlei (Mem. Indian Mus., 2, 1909; 45), has been empha- 

 sized recently by Cox and Breder (Zoologica N. Y., 28, 1943: 47) for N. brasiliensis. 



120. Giinther's (Cat. Fish. Brit. Mus., 8, 1870: 453) report oi Narcine brasiliensis from the Cape of Good Hope probably 

 was an error, for Narcine has not been found during recent surveys of the fish fauna of South African waters (von 

 Bonde and Swart, Fish. Mar. biol. Surv. S. Afr., Rep. 3 [1922], 1924, Spec. Rep. i ; Barnard, Ann. S. Afr. Mus., 

 21 [i], 1925: 91). 



121. The type species of Heteronarce, H. garmani Regan (Ann. Mag. nat. hist., [9] 7, 1921 : 414), is reported so far only 

 from the coast of Natal. Narcine mollis Lloyd (Rec. Indian Mus., i, 1907: 5), also referred to Heteronarce by Re- 

 gan, is known only from the Gulf of Aden. 



122. Narcine brasiliensis (p. 112); A^. indica from Penang; N.Ungida from Penang; N. timlei from China; N. mermiculata, 

 and the form previously called N. entemedor which probably is not separable from N. brasiliensis, from the west 

 coast of Central America. 



123. Gen. Zool., 5(2), 1804: 316. 



