534 Mr. C. T. Regan on the Myxlnoids of the 



LIX. — A Synopsis of the Myxlnoids of the Genus Hepta- 

 tretus or Bdellostoma. By C. Tate Regan, M.A. 



(Published by permission of the Trustees of the British Museum.) 



Heptatretus. 



Eptatretus, Cloquet, Diet. Sci. Nat. xv. p. 134 (1819). 

 Homea, Fleming, Philos. of Zool. ii. p. 375 (1822). 

 Ileptatrema, Voigt, Thierr. ii. p. 529 (1832). 

 Bdellostoma, Miill. Abhandl. Akad. Berlin, 1834, p. 79. 

 Polistotrema, Gill, Proc. U.S. Nat. Mus. 1880, p. 30. 



Myxlnoids with 6 to 14 brancliial apertures on eacli side 

 and with the external branchial ducts subequal in length. 



Pacific coast of America ; Japan ; New Zealand ; Cape of 

 Good Hope. 



The specimens enumerated are those in the British Museum 

 Collection, on which this revision is based. 



Synopsis of the Species. 

 I. 14 gill-openings 1. pohjtrema. 



II. 11 to 13 gill-openings. 



Length of head, to first gill-openiug, more than | of the 



total length 2. sfouti. 



Length of head, to first gill-opening, less than 1 of the 



total length 3. dea?i{. 



III. 10 gill-openings. 4. decatrema. 



IV. 8 gill-openings 5. oJihwseanus. 



V. 7 gill-openings. 



Teeth i| | g 6. drratus. 



Teeth |l ? 7. banksii. 



VI. 6 gill-openings. 



\2 I 12 



or 12 ! 11 or 



Teeth — t g 9. biurgeri. 



Teeth ., "^ .., 8. hexatrema. 



11 or 12 1 11 or 12 



1. Heptatretus polytrema. 



Bdellostoma polytretna, Girard, Proc. Ac. Philad. 1854, p. 199, and 

 U.S. Nav. Astrou. Exped., Zool. p. 252, pi. xxxiii. (1856) ; Giinth 

 Cat. Fish. viii. p. 512 (1870). 



14 gill-openings ; two rows of 12 tooth on each side, the 3 



