434 Memoir Sears Foundation for Marine Research 



villi that clothe the walls of the maternal uterus. This fluid is taken in through the 

 embryonic spiracles and mouth, and probably it is absorbed by the external embryonic 

 gill filaments as well, so long as these persist. By the time the embryos have lost their 

 external gills and have absorbed the yolk sac, they already approach their parents in 

 general form and proportions; their subrostral fins already project more or less beyond 

 the front of the cranium, the posterior margin of the nasal curtain is fringed,^ the tooth 

 pattern is at least forecast, and the color pattern is established. 



Range. Tropical to temperate latitudes of all three great oceans, including the 

 Mediterranean Sea, both in continental waters and around the larger offlying islands 

 and island groups. Southwest Africa to southern England, Scotland, and (rarely) south- 

 ern Norway in the eastern Atlantic; northern Argentina to southern New England in 

 the western Atlantic. 



Genera. The members of the family fall into four groups (see Key, p. 434), depend- 

 ing on the following characters: one series of teeth in each jaw or more than three 

 series; rostral sectors of the pectorals connected or not with the main portions of the 

 fins by a continuous series of cartilaginous rays along the sides of the head; and tail 

 armed or not with a spine (or spines). Thus, the taxonomic picture is a simple one so 

 far as generic divisions are concerned. But the generic nomenclature within the family 

 has been confused by uncertainty as to the authorships and dates (and hence as to type 

 species) that are to be assigned to the genera Myliobatis and Aetobatus.,* which were the 

 earliest names proposed for any members of the family when separated from the old 

 Linnean genus Raja. 



In applying the name Myliobatis Cuvier 18 17 to members of the family with more 

 than three series of teeth and with the rostral portions of the pectorals united with the 

 chief portions of the fins along the sides of the head, we follow Garman^ rather than 

 Fowler,^ who applied it to those with several series of teeth but with the pectorals 

 entirely interrupted. 



Key to Genera 



I a. Only a single series of teeth in each jaw. Aetobatus Blainville 18 16, p. 451. 



3. See p. 459 for Aetobatus narinari; see also Southwell and Prashad (Rec. Indian Mus., i6, 1919: 233, pi. 19, figs. 4, 

 4a) for an account and illustrations of the embryos oi Aetomylaeus nichofii (Bloch and Schneider) 1801, of the western 

 Pacific-Australia area, East Indian region, and Indian Ocean. 



4. Aetobatus Blainville 1816 (Bull. See. philom. Paris, 1816: 112) properly applies to myliobatids with only one series 

 of teeth, since the 1 1 species that Blainville mentioned by name included narinari (doubtless the Raja narinari of 

 Euphrasen 1790), which was designated as type species by Gill (Proc. U. S. nat. Mus., 77, 1894: in). Myliobatis 

 Cuvier 1817, type species Raja aquila Linnaeus 1758, with several series of teeth and pectorals continuous along 

 the sides of the head, appears to antedate Myliobatis G. St.-Hilaire, type species M. bo'uina St.-Hilaire, with pectorals 

 entirely interrupted along sides of head (designated by Fowler, Bull. geol. Surv. N. J., 4, 191 1 : 84). Although the 

 title page of the volume that contains St.-Hilaire's account of Myliobatis (Savigny, Zool. Egypte, i) is dated 1809, 

 the plate in question appeared in 18 17 (according to Isidore G. St.-Hilaire, Vie, Travaux . . . Etienne Geoffrey 

 St.-Hilaire, 1847: 425), and the pages in question (Poiss. Mer Rouge, pp. 323, 334) were not printed until about 

 1827 (Sherborn, Proc. zool. See. Lond., 1897: 386). Aetobatis Blainville 1825 (in Vieillot, Faune Fran?., Poiss., 

 1825: 38) clearly is a synonym of Myliobatis Cuvier 1817, since its type (and only included) species was the same. 

 But Aetobatis Muller and Henle 1841 is equivalent to Aetobatus Blainville 18 16, as is Stoasodon Cantor 1849 (Malay. 

 Fish., J. roy. Asiatic Soc, iS, 1849: 1416). 



5. Mem. Harv. Mus. comp. Zool., 36, 1913: 428. 6. Bull. U.S. nat. Mus., 100 (13), 1941: 469. 



