[B. nakagawae, Jord. and S.—Myotomes 37 + 16 + 11: Japan.
[B. caribbaeum, Sundevall—Myotomes 37 + 14 + 9: West Indies, Atlantic, N. and S. America.
B. capense, Gilchrist—Myotomes 47 + 19 + 9: S. Africa.
B. californiense, J. G. Cooper—Myotomes 45 + 17 + 9: California.
B. (Dolichorhynchus) indicum (Willey)—Myotomes 42 + 14 + 15: India and Ceylon.
(?) B. elongatum, Sundevall—Myotomes 49 + 18 + 12: Peru.
(?) B. pelagicum, Günther—Myotomes 36 + 16 + 15: Honolulu, Gulf of Manaar, South Indian Ocean.
Genus 2. Asymmetron (Andrews, 1893).
With uniserial (right) gonads and asymmetrical metapleura.
A. lucayanum, Andrews—Myotomes 44 + 9 + 13: Bahamas, Maldives, Zanzibar.