1 8 Memoir Sears Foundation for Marine Research 



range); Schreiner and Ribeiro, Arch. Mus. nac. Rio de J., 12, 1903: 77 (Santa Catharina, Brazil, prob- 

 ably B. flatae because of loc.) ; Marelli, Elenc. Sist. Fauna B. Aires (Procord. Vert.) ; Mem. Ministr. 

 Obras Publ. B. Aires (1922-1923), Fishes, 1924: 543 (no descr., Rio de Janeiro, Rio de La Plata, 

 Buenos Aires, ident. probably because of loc.) ; Luderwaldt, Rev. Mus. paul., 16, 1929: 40 (San Sebastlao 

 I., Brazil) ; Sawaya and Carvalho, Bol. biol. Fac. Med. S. Paulo, N.S. 2, 1938: 43 (no. of myotomes, be- 

 havior in aquarium, Santos, Brazil, at 2; meters). 

 Amfhioxos (no specific name) Luderwaldt, Rev. Mus. paul., 16, 1929: 11,15 ('" plankton, and from bottom 

 in shallow water, San Sebastiao L, Brazil). 



Family EPIGONICHTHYIDAE 



Description. Gonads developed on right side onlyj right-hand metapleuron continu- 

 ous with preanal fin. Characters otherwise those of the order.^* 



Genera. The family includes two well defined genera: in Epgonichthys the caudal 

 fin does not extend as a long narrow process, and the oral tentacles are united, one to the 

 next, by a uniformly low intertentacular membrane; in Asymmetron the caudal fin, as well 

 as the notochord, is much prolonged posterior to the myotomes as a narrow process, and the 

 intertentacular membrane is much higher ventrally than laterally. 



Key to Genera 



la. Caudal fin prolonged as a narrow process; the intertentacular membrane much higher 

 ventrally than laterally (Fig. 3). Asymmetron Andrews, 1893, p. 18." 



lb. Caudal fin not prolonged as a narrow process; the intertentacular membrane but little 

 higher ventrally than laterally. Efigonichthys Peters, 1876.^° 



New Zealand; Australia; East Indies; 

 Ceylon; Maldive and Laccadive Ar- 

 chipelagos, to East Africa. 



Genus yii'yww^/row Andrews, 1893 



Asymmetron Xnix^yii, Stud. Biol. Lab. Johns Hopk. Univ., 5, 1893: 237; type species, A. lucayanum Andrews. 

 Bahamas.'^ 



Generic synonyms: 



Branchiostoma (in part) Willey, Amphioxus and Ancest. Vert., 1894: 41 ; including A. lucayanum Andrews, 



1893 ; not Branchiostoma Costa, 1834. 

 Efigonichthys Fowler, Proc. Acad. nat. Sci. Philad., 59, 1907: 461 ; including A. lucayanum Andrews, 1893; 



not Efigonichthys Peters, 1876. 



34. Whitley (Aust. Zool., 7, 1932: 257, 260) divides this family into Epigonichthyidae and Asymmetrontidae. 



35. Including Notasymmetron Whitley (Aust. Zool., 7, 1932: 260, pi. 13, fig. 6). Whitley mentions, as characters 

 distinguishing this genus from Asymmetron, only that it is larger, with the origin and termination of the dorsal 

 fin farther forward in relation to the myotomes. 



36. Including Bathyamfhioxus and Merscal-pellus Whitley, 1932. The differences on which Whitley (Aust. Zool., 7, 

 1932: 257—259) has separated these two new genera from Efigonichthys are so small that we hesitate to judge 

 their validity, not having seen specimens of them. Paramfhioxus Haeckel, 1893, is clearly a synonym of 

 Efigonichthys Peters, 1876, in our opinion. 



37. The characters of this new genus were given also, but without a generic name, by Andrews (Johns Hopk. Univ. 

 Circ, 72, 1893 : 104). 



