Fishes of the Western North Atlantic 45 



bilobed (Fig. 7) with deeply concave posterior margin; both upper and lower lobes 

 sharp-tipped; caudal axis moderately raised, its termination near posterior margin of 

 fin some distance below tip of upper lobe. Eyeballs with low rounded velum above 

 pupil, the orbits outlined below and anteriorly by a deep furrow. Spiracles large, about 

 as broad as long, close to eyes and either transverse or only slightly oblique, with inner 

 ends directed rearward, their posterior margins with or without transverse folds. Rostral 

 projection from cranium extending to tip of snout. 



Genera. Two genera, Rhynchobatus and Rhina, are generally recognized. 



Key to Genera. 



I a. Snout narrow, pointed, its length in front of eyes nearly or quite as great as breadth 

 of head at level of anterior margins of eyes; posterior margin of spiracles with 

 two low vertical ridges; mouth only slightly undulate, with median projection of 

 lower jaw fitting a corresponding depression of upper. 



Rhynchobatus^ Miiller and Henle 1837 

 Tropical Indian Ocean, including Red Sea, south to 

 Natal; tropical West Africa; Malay Peninsula; Phi- 

 lippines; East Asia north to Japan; Australia.' 

 lb. Snout broadly rounded, its length in front of eyes much less than breadth of 

 head at eyes; posterior margin of spiracles without vertical ridges; mouth strongly 

 undulate, with three forward projections of the lower jaw alternating with two 

 rearward indentations of the upper. Rhina Bloch and Schneider 1801.* 



Tropical Indian Ocean in general, including 

 the Red Sea and the Gulf of Oman; Malayan 

 region; East Indies; Philippines; Australia; 

 southeastern coasts of Asia northward to sou- 

 thern China and Japan.* 



6. Rhinobatis Blainville 1825 (in Vieillot, Faune Franf., 1825: 47, 48) may have been an earlier name for the genus 

 now known as Rhynchobatus (see p. 51, footnote), but we think it wiser to regard it as preoccupied by Rhinobatos 

 Link 1790, since the use of names differing by only one letter for two different genera within the same suborder 

 could only lead to confusion. 



7. The type species (the only species known until recendy) is Rhynchobatus djiddensis (Forskal) 1775 of the Indo- 

 Pacific. A separate subspecific name, australiae, has been proposed by Whitley (Aust. Zool., 9, 1939: 245; Fish. 

 Aust., I, 1940: 173, fig. 197) for Australian specimens whose form is wider toward the root of the tail and whose 

 color pattern differs from the typical Rhynchobatus djiddensis. But a small specimen of the latter from Ceylon, 

 examined by us, agrees so closely in both these respects with Whitley's accounts and illustration of his australiae 

 that it seems unnecessary to retain that name. 



Three additional species have been described from tropical West Africa: Rhynchobatus liibberti Ehrenbaum 

 (Fischerbote, 6, 1914: 303), with which R. atlanticus Regan (Ann. Mag. nat. Hist., [8] 4, 1915: 124) appears to 

 be identical, Rhynchobatus albomaculatus (Norman) (Ann. Mag. nat. Hist., [10] 6, 1930: 226), and Rhynchobatus 

 ir^inei (Norman) (Ann. Mag. nat. Hist., [10] 7, 1931: 352). The last two were originally placed in Rhinobatos 

 but are clearly referable to Rhynchobatus by their bilobed caudals. 



8. The name Rhina was first used by Schaeffer (Epist., Stud. Ichthyol., 1760: 20) for the Shark genus properly known 

 as Squatina, then by Klein (Neuer Schauplatz, 2, 1776: 587), by Walbaum (P. Artedi Genera Pise. Emend. Ichthyol., 

 1792: 58), and by some more recent authors. However, Schaeffer did not include any species in his genus Rhina, 

 and the International Commission on Zoological Nomenclature has ruled (Opin. Rend., Smithson. Publ., No. 

 1938, 1910: 51; Smithson. miscell. Coll., 7J [3], 1925: 27) that neither Klein's names, nor Walbaum's revival of 

 them, are to be taken into account. Consequently, Rhina as a generic name must date from Bloch and Schneider 

 (Syst. Ichthyol., 1801: 352, pi. 72), who applied it to an Indian Ray with the specific name R. ancylostomus. 



9. For list of localides recorded for Rhina ancylostoma Bloch and Schneider 1801, see Fowler (Bull. U. S. nat. Mus., 

 100 [jj], 1941: 299). 



