Fishes of the JVestern North Atlantic 49 



2 b. Expansions of anterior margin of nostrils united to form a single broad quad- 

 rangular curtain, the free edge close to upper lip, with which it is united at 

 isthmus (Fig. 9). Trygonorhina}^ Miiller and Henle 1841. 



Australia. 

 lb. Snout rounded; tips of anterior rays of pectorals reaching nearly or quite to tip 

 of snout. 

 5 a. Rostral cartilage extending nearly or quite to tip of snout. 



6a. Dorsal surface of tail with three rows of prominent thorns; origin of first 

 dorsal much nearer to origin of second dorsal than to rear tips of pelvics; 



Figure ii. Xanobatus schoenleinii. Nostril 

 with inner end to the left; after Norman. 



lobe-like expansion of anterior margin of nostril almost entirely covering 

 inner end of nasal aperture; posterior margin of nostril only slightly 

 expanded (Fig. 10). Flatyrhinoidis Garman 1881. 



Coast of California from Point Con- 

 ception southward.^® 

 6b. Dorsal surface of tail with only one median row of large thorns; origin 

 of first dorsal about midway between rear tips of pelvics and origin of 

 second dorsal; lobe-like expansion of anterior margin of nostril leaving 

 inner part of nasal opening exposed; posterior margin of nostril expanded 

 as a broad rounded flap (Fig. 11). Zanobatus Garman 1913. 



India and tropical West Africa. 2" 



clearly congeneric with Rhinobatos [Syrrhina] bre'-oirostris MuUer and Henle 1841. But, since this revival of Syr- 

 rhina had been antedated by Jordan and Gilbert's (Proc. U. S. nat. Mus., 3, 1880: 53) proposal of the generic 

 name Zapteryx for exasperata, we follow prevalent usage (Jordan and Evermann, Bull. U. S. nat. Mus., 47 [i], 

 1896: 64; Jordan, Genera Fish., 2, 1919: 192; Norman, Proc. zool. Soc. Lond., 1926: 979; Beebe and Tee-Van, 

 Zoologica N. Y., 26, 1941 : 252) in employing Zapteryx and in relegating Syrrhina to the synonymy of Rhinobatos. 

 See also under generic synonyms of Rhinobatos, p. 50. 



18. One species, Trygonorhina fasciata MuUer and Henle 1841, with color varieties. These appear to be genetic rather 

 than environmental, for specimens experimented upon showed only slight alterations in shade on white and on 

 black backgrounds (Griffiths, Proc. Linn. Soc. N. S. \V., 61, 1936: 319). For an account of the skeleton of Try- 

 gonorhina, see Haswell (Proc. Linn. Soc. N. S. W., g, 1884: 107, pi. 2, figs. 1-5). 



19. One species only, the Platyrhina triseriata of Jordan and Gilbert (Proc. U. S. nat. Mus., J, 1880: 36), for which 

 Garman (Proc. U.S. nat. Mus., j, 1881: 522) proposed the genus Platyrhinoiiiis. 



lo. Illustrations of the adult of this genus (Muller and Henle, Plagiost., 1841 : pi. 45; Steindachner, Denkschr. Akad. 

 Wiss. Wien, .^4, 1882: pi. 7) seem to picture the rostral cartilage as extending nearly or quite to the tip of the snout. 

 But it appeared not to reach the extremity of the snout in a very young one examined by Norman (Proc. zool. Soc. 

 Lond., 1926: 982). The West African form, originally reported and pictured by Steindachner as Platyrhina schoen- 

 leinii Muller and Henle 1841, has been redescribed recently by Chabanaud (Bull. Soc. zool. Fr., 53, 1928: 419) 

 as a separate species, Platyrhinoidis atlantica. 



