IV CLASSIFICATION 7 
to that of the Tunicata (see p. 55), but lends no support. to 
the view that Amphioxus has degenerated from a higher group 
of the Vertebrata. 
Classification of the Cephalochordata. 
The known species of Amphioxus may be classified as 
follows * :— 
Famity BRANCHIOSTOMATIDAR, 
Genus 1. Branchiostoma (Costa, 1834). 
Having biserial gonads and symmetrical metapleura. 
B. lanceolatum (Pallas)—Myotomes 36+4+14+4 12, gonads 28-29 pairs: 
Mediterranean, N.W. Europe, Ceylon, E. of United States. 
[B. belchert, Gray —Myotomes 38+17+9: Torres Straits, Singapore, 
Borneo, Ceylon. 
[B. nakagawae, Jord. and S.—Myotomes 37+16+11: Japan. 
[ B. caribbaewm, Sundevall—Myotomes 37 +1449: West Indies, Atlantic, 
N. and 8S. America. 
B. capense, Gilchrist—Myotomes 47+ 19+9: 8S. Africa. 
B. californiense, J. G. Cooper—Myotomes 45+17+9: California, 
B. (Dolichorhynchus) indicum (Willey)—Myotomes 42+4+14+4+15: India 
and Ceylon. 
(2) B. elongatum, Sundevall—Myotomes 49+ 18+412: Peru. 
(2) B. pelagicum, Ginther—Myotomes 36+16+15: Honolulu, Guwif 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. 
A. caudatum (Willey)—Myotomes 40+9+11: Louisiade Archipelago. 
A. (Heteroplewron) bassanwm (Ginther)—Myotomes 454+ 16+4+14: Bass 
Straits, Australia. 
55 cingalense (Kirkaldy)—Myotomes 39+ 16+ 8: Ceylon. 
= cultellum (Peters)—Myotomes 32+4+10+10: Torres 
Straits, Australia, Ceylon. 
- maldivense (F. Cooper)—Myotomes 45 +16+12: Mal- 
dive Archipelago, Zanzibar. 
2 hectort (Benham)—Myotomes 534+ 19+12: New Zea- 
land. 
1 T have to thank Mr. Walter Tattersall, B.Sc., working in my laboratory, for 
a detailed summary and discussion of the various published schemes from which 
this table has been drawn up. He has also filled up for me the map (Fig. 90) 
showing the geographical distribution of the species. (See also Trans. Biol. Soc. 
Liverpool, vol. xvii. 1908, p. 269.) 
